The Transmission of Early Bronze Technology to Thailand: New Perspectives

In the four decades since the discovery that a discrete Bronze Age preceded the Iron Age in mainland Southeast Asia, much has been learned about the dating, technology, production, organization, and use of bronze metallurgy in the region, particularly in prehistoric Thailand. Although independent invention of copper smelting in Southeast Asia has not been considered likely by most regional archaeologists since the 1980s, the source of copper-base technology and the mechanisms of adoption remain poorly understood. Arguments claiming that the primary stimulus for the appearance of copper-base metallurgy in Southeast Asia came from early states in the Central Plain of China have dominated recent discussions, but anthropological approaches to technology transmission, adoption, and adaptation have yet to be systematically explored. After summarizing the current evidence for early bronze metallurgy in Thailand, this paper proposes an alternative to the predominant Sinocentric view of the source for Southeast Asian bronze technology. It will be proposed on both chronological and technological grounds that the first bronze metallurgy in Southeast Asia was derived from pre-Andronovo late third millennium BC Eurasian forest-steppe metals technology, and not from the second millennium, technologically distinctive, élite-sponsored bronze metallurgy of the Chinese Erlitou or Erligang Periods. Hypotheses for a transmission route and a research agenda for resolving debates on bronze origins in Southeast Asia are offered.     

The potential of stable Cu isotopes for the identification of Bronze Age ore mineral sources from Cyprus and Faynan: results from Uluburun and Khirbat Hamra Ifdan

Copper isotope ratios differ between hypogene sulfidic, supergene sulfidic and oxidized ore sources. Traditional lead isotope signatures of ancient metals are specific to deposits, while Cu isotope signatures are specific to the types of ore minerals used for metal production in ancient times. Two methodological case studies are presented: First, the mining district of Faynan (Jordan) was investigated. Here, mainly oxidized copper ores occur in the deposits. The production of copper from Fayan’s ore sources is confirmed by the measurement of the Cu isotope signature of ingots from the Early Bronze Age metal workshop from Khirbat Hamra Ifdan. Based on our results illustrating differences in the Cu isotope composition between the ore mineralizations from Timna (Israel) and Faynan, it is now possible to determine these prehistoric mining districts from which copper artifacts originated by combining trace elements and Pb isotopes with Cu isotopes. The second case study presents data on Late Bronze Age copper production in Cyprus. Oxhide ingots from the shipwreck of Uluburun (Turkey) were tested for their lead isotope signatures and assigned to Cypriot deposits in the recent decades. The oxhide ingots from Uluburun show a Cu isotope signature which we also found for oxidized copper ores from Cyprus, while younger oxhide ingots as well as metallurgical slag from the Cypriot settlements Kition and Enkomi show a different signature which might be due to the use of sulfidic ore sources from a greater depth of deposits. We assert that there could be a chronological shift from oxidized to sulfidic ore sources for the copper production in Cyprus, requiring different technologies. Therefore, Cu isotopes can be used as a proxy to reconstruct mining and induced smelting activities in ancient times.     

The Determination of Lead Isotope Ratios by Multiple Collector Icp‐Ms: A Case Study of Early Bronze Age Artefacts and their Possible Relation With Ore Deposits of the Erzgebirge*

Lead isotope analyses of Early Bronze Age metal artefacts from the Aunjetitz (Ún?tice) culture in central Germany and Bohemia were determined in order to find out whether they could be related to ore sources of the Erzgebirge. Historical mining began only in the 12th century ad , but despite the lack of convincing field evidence it has frequently been suspected that this region was already being exploited in prehistoric times. For the determination of the lead isotope ratios, the new technique of multiple collector inductively coupled plasma mass spectrometry (MC‐ICP‐MS) was employed, which combines relatively easy sample preparation with highly precise and accurate measurements. The results show that there is still no evidence for prehistoric mining in the Erzgebirge, but the Rammelsberg deposit in the Harz Mountains might have supplied some of the copper. Mining of stream tin in the Erzgebirge remains a possibility, but no positive evidence can be extracted from the data.     

Prehistoric copper production and technological reproduction in the Khao Wong Prachan Valley of Central Thailand

This paper concerns the identification and explanation of change in prehistoric extractive metallurgical behaviour in the Iron Age Khao Wong Prachan Valley of central Thailand. This metallurgical complex is amongst the largest in Eurasia and constitutes Southeast Asia's only documented pre-modern copper-smelting evidence. The two Iron Age smelting sites investigated, Non Pa Wai (NPW) and Nil Kham Haeng (NKH), provide a sequence of metallurgical consumption and production evidence from c. 500 BCE to c. 500 CE. The enormous quantity of industrial waste at these sites suggests they were probably major copper supply nodes within ancient Southeast Asian metal exchange networks. Seventy-six excavated samples of mineral, technical ceramic and slag from NPW and NKH were analysed in hand specimen, microstructurally by reflected-light microscopy and scanning electron microscopy and chemically by polarising energy-dispersive X-ray fluorescence spectrometry and scanning electron microscopy with energy-dispersive X-ray fluorescence spectrometry. The analytical data were used to generate detailed technological reconstructions of copper-smelting behaviour at the two sites, which were refined by a programme of field experimentation. Results indicate an approximately 1,000-year trend of Valley copper smelters' improving technical proficiency from what may be an experimental phase of production in the mid-first millennium BCE. This amelioration in production was accompanied by a substantial increase in the human effort of copper extraction. This shift in local ‘metallurgical ethos’ is interpreted as a response to rising regional demand for copper in late prehistory.     

Recent Developments in the Archaeology of Southwestern China

Archaeology of ancient China’s periphery has traditionally been examined through the historiographic lens of Chinese textual sources. Social developments in the periphery are often explained in relation to accounts of migration from “core” regions of China. Setting conventional paradigms and textual sources aside, this article examines prehistoric developments in southwestern China in conjunction with broader trends in Southeast Asia. This comparative approach reveals that the development of bronze metallurgy in southwestern China parallels trends observed among Neolithic communities in Southeast Asia. Using recent data and a reassessment of radiocarbon dates for the Bronze Age, I propose that sociopolitical complexity emerged in southwestern China as part of a multiregional phenomenon that had its beginning with the formalization of trade networks during the Neolithic period.     

LEAD ISOTOPE ANALYSES OF BRONZE AGE COPPER‐BASE ARTEFACTS FROM AL‐MIDAMMAN,YEMEN: TOWARDS THE IDENTIFICATION OF AN INDIGENOUS METAL PRODUCTION AND EXCHANGE SYSTEM IN THE SOUTHERN RED SEA REGION*

The results of the lead isotope analysis (LIA) of 15 copper‐base artefacts from the Bronze Age site of al‐Midamman, Yemen, are reported. The LIA data suggest the existence of an indigenous Bronze Age metal production and exchange system centred on the southern Red Sea region, distinct from those in neighbouring regions of Arabia and the Levant. These preliminary results are highly significant for the archaeology of the region, suggesting that local prehistoric copper extraction sites have thus far gone unrecorded, and highlighting the need for systematic archaeometallurgical fieldwork programmes in the countries surrounding the southern Red Sea.     

Isotopic and technological variation in prehistoric Southeast Asian primary copper production

The ‘Southeast Asian Lead Isotope Project’ (SEALIP) is intended to provide reliable geochemical proxies for late prehistoric through early historic (2nd/1st millennium BCE and 1st millennium CE) local, regional, and inter-regional social interactions, in an archaeological arena lacking established ceramic typologies with which to cross modern national boundaries. We present lead isotope characterisations of the three currently known Southeast Asian prehistoric primary (mining/smelting) copper production centres: Phu Lon and the Khao Wong Prachan Valley in Thailand, and the recently discovered Xepon complex in Laos. Kernel Density Estimation shows that these production centres can be clearly distinguished isotopically, as such fulfilling the core tenet of the ‘Provenance Hypothesis’ (Wilson and Pollard, 2001: 508) and permitting SEALIP to proceed as a research programme tracing regional copper/bronze/lead exchange and provenance patterning. In addition we provide a provisional technological reconstruction of copper smelting processes at Phu Lon to complement our more established understanding of the Khao Wong Prachan Valley. Combined lead isotope and technological datasets allow us to tentatively identify trends in the evolution of Southeast Asian metal technologies and of regional social perceptions of metal exchange.     

Provenance of Early Bronze Age metal artefacts in Western Switzerland using elemental and lead isotopic compositions and their possible relation with copper minerals of the nearby Valais

Ten Early Bronze Age (BzA1, 2200–2000 BC) copper artefacts from the central Valais region from Switzerland were studied for their elemental composition and lead isotope ratios. In order to answer the archaeological question of a local copper supply, a database for copper minerals across the Valais (Switzerland) has been established. This database contains 69 data on lead isotope ratios as well as additional information on the minerals and geochemical associations for copper minerals from 38 locations in the Valais. Comparisons of the artefacts were also made with data pertaining to minerals from various deposits from Europe and Anatolia taken from the literature. The provenance of the materials is very diverse. Some of the data are compatible with the data from the copper mineral deposits of the Valais region. Moreover, three copper lunulae were identified as possibly Tuscan, which suggests contacts between Italy and the Valais region. This pattern also establishes a multiplicity of provenances for the metal and cultural influences in the Alpine environment of the Rhone Valley of Switzerland at the beginning of the Early Bronze Age.     

THE ORIGIN of METAL OBJECTS FROM the EARLY BRONZE AGE SITE of THERMI ON the ISLAND of LESBOS

Summary: Lead isotope analysis of metal are deposits in the Mediterranean provides an important database for provenance studies of ancient metal artefacts. the Isotrace laboratory at Oxford has accumulated during the past decade well over 2000 lead isotope data on copper and lead ores and these data (in addition to analyses published by other groups) can be used for comparisons with lead isotope compositions of ancient metal objects. In a search for the roots of Early Bronze Age metallurgy in Europe we have analysed 34 copper-based objects from the Early Bronze Age strata of the town of Thermi on the Aegean island of Lesbos. the results of lead isotope analysis show that the metal objects on this site have a quite varied origin. Some of the objects are made of copper consistent with an origin from the mineral deposits of the Troad whilst others might be made of copper from the Cyclades. However, there are also some objects which are not made of copper from any of the Aegean deposits. These imports have later parallels on the site of Kastri on Syros and amongst the objects excavated by Schliemann at Troy.     

SOUTHEAST ASIA'S FIRST ISOTOPICALLY DEFINED PREHISTORIC COPPER PRODUCTION SYSTEM: WHEN DID EXTRACTIVE METALLURGY BEGIN IN THE KHAO WONG PRACHAN VALLEY OF CENTRAL THAILAND?

Southeast Asian metallurgical developments have been a focus of international academic interest since Solheim (1968 ) and Bayard (1972 ) first published bronze artefacts in claimed early/middle third millennium bce contexts from northeastern Thailand, igniting a regional ‘origins’ of metallurgy debate that has smouldered for 40 years (e.g., White and Hamilton 2009 , Higham in press ). In this paper, we present the results of a lead isotope pilot study centred on the Khao Wong Prachan Valley of central Thailand—currently Southeast Asia's only documented prehistoric copper smelting locale. These preliminary data indicate that our ongoing regional metal exchange research programme may be able to elucidate interaction networks between copper‐producing and ‐consuming societies within and beyond Southeast Asia from c. 2000 bce to c. 500 ce . Furthermore, we are able to offer tentative evidence relevant to White and Hamilton's (2009 ) ‘Rapid Eurasian Technological Expansion Model’ for the Sino‐Siberian derivation of regional metal technologies around the turn of the third/second millennium bce .     

Early Cambodian gold and silver from Prohear: composition,trace elements and gilding

Rescue excavations in Prohear, southeast Cambodia, recently saved the last untouched graves of one of the richest prehistoric sites in Southeast Asia. Many Iron Age burials dating from the 2nd century BC to the 1st century AD contained gold and silver ornaments so far unknown from archaeological contexts together with indications for the presence of an immigrated elite. A first selection of 59 objects were analysed by LA-ICP-MS to obtain detailed information about the composition, as well as minor and trace elements. The majority of the ornaments consist of electrum and auriferous silver with low copper concentrations, and two main groups indicating different alluvial gold sources can be distinguished by different concentrations of Pt, Ir, Bi and different Pd/Pt ratios, one group being related to rich burials with non-local features. The SEM and EDX analyses of four objects revealed two different gilding techniques observed for the first time in Southeast Asian artefacts: foil-fusion gilding, related to special Ag–Au–(Cu)–Sn alloys containing up to 4% tin, and depletion gilding.     

The Mineralogy of Bronze Age Copper Ores from the British Isles: Implications for the Composition of Early Metalwork

Numerous analytical studies during the latter half of this century have contributed to the compilation of a large compositional database of Early to Middle Bronze Age copper-based artefacts revealing distinctive impurity patterns which appear to change over time. However, attempts to relate these data to copper ore sources proved problematic in the absence of firm evidence for the location of prehistoric copper mines. Over the last fifteen years this situation has changed dramatically with the discovery of numerous Early and Middle Bronze Age copper mines in England and Wales. This study is the first attempt at a comprehensive mineralogical survey of the principal mines investigated to date in order to define the likely composition of the copper ores as mined in antiquity for comparison with the artefact database. The study suggests that the majority of these mines can only have produced essentially pure copper. Only one mine, Ross Island, is likely to have produced copper with a significant level of impurities. The relative purity of the known ore sources is contrasted with significant levels of various metallic impurities among the analysed artefacts, leading to the conclusion that metal circulation and mixing may have been more extensive than previously thought even during the earliest part of the Bronze Age.     

LEAD ISOTOPE CHARACTERISTICS OF THE CYPRUS COPPER ORE DEPOSITS APPLIED TO PROVENANCE STUDIES OF COPPER OXHIDE INGOTS

Nearly 200 new lead isotope analyses of sulphidic and oxidized ores from 26 copper mines on Cyprus show that the mines from different geological regions group in five distinctive isotopic groups, each with a substructure, related to the geological history of the ore formation. Comparison of lead isotope compositions of Bronze Age artefacts with these data can in many cases reveal the actual mines from which the copper for particular artefacts was obtained. The particular case of the provenance of the copper for 78 Late Bronze Age copper ‘oxhide ingots’found in Cyprus, Crete, Greece, Sardinia, Turkey and Bulgaria is discussed. The data show that all oxhide ingots so far analysed, dating to the fourteenth century BC and later, were made of copper consistent isotopically with only one mining region in the geographical north of Cyprus, and especially the Apliki mine. The study provides further evidence which supports the validity of the conventional approach to the use of lead isotope analysis for provenancing metals; this evidence is antithetical to recent suggestions of a model for the production of copper oxhide ingots which involved widespread mixing of copper from a number of ore sources throughout the Mediterranean.     

Intrinsic or extrinsic population growth in Iron Age northeast Thailand? The evidence from isotopic analysis

Here we present strontium, carbon and oxygen isotope measurements from the tooth enamel of 34 adults from Noen U-Loke, an Iron Age site (c. 300BC–500AD) in the Upper Mun River Valley (UMRV), northeast Thailand. The Mun Valley is rich in archaeological sites from the Bronze Age to the Iron Age, with evidence for changes in social complexity, new technologies and population growth. Whether the population growth in the UMRV was intrinsic, as opposed to extrinsically due to immigration, is an unresolved question. Our results suggest low levels of long-distance immigration, with only three (two females, one male) of the thirty-four individuals as probable immigrants from outside the region. We discuss the implications of this result as a contribution to longer-term investigations of population growth, human mobility and fertility during this prehistoric period of substantial societal changes in mainland Southeast Asia.     

Reassessment and new data on the diachronic relationship of Thassos Island with its indigenous metal resources: a review

The extraction of mineral ores and its associated metal production has been a persistent element of the economy on Thassos Island since prehistoric times. As early as the Upper Palaeolithic, around 20,000 years ago, ochre had been mined and used for painting, while early silver extraction is attested during the Final Neolithic (early fourth millennium BC). Copper production and alloying becomes an important activity in the coastal settlements of the island during the third and second millennia. The inception of iron metallurgy has been seen in association with copper smelting as confirmed by analyses on slag found in Early Iron Age upland cemeteries. With the arrival of the Greek colonists around 650 BC, intensification in silver and gold extraction became paramount for further economic expansion. This deep history in the use of Thassian metals is being reviewed based on archaeological findings and archaeometallurgical research of the last three decades, while new analytical data on Early Bronze Age copper smelting at Aghios Antonios are being presented.     

Strontium isotope analysis of Neolithic and Copper Age populations on the Great Hungarian Plain

The strontium isotope ratio (⁸⁷Sr/⁸⁶Sr) is used in archaeological studies to identify major events of population movement in prehistory such as migration, conquest, and inter-marriage. This study shows that the strontium isotope method can be expanded to identify more subtle shifts in prehistoric human mobility. ⁸⁷Sr/⁸⁶Sr isotope ratios were analyzed in dental enamel from human and faunal specimens from the Late Neolithic and Copper Age on the Great Hungarian Plain. The archaeological record indicates that several aspects of life changed during the transition from the Late Neolithic to the Copper Age (ca. 4500 BC) in Hungary; evidence for increased interaction over a wide geographical area, less resource pooling and the use of secondary products has been used to support the idea that local populations became more mobile, perhaps due to the adoption of an agro-pastoral economy. Results from this study identify a change in the range of strontium isotope values from the Late Neolithic to the Copper Age from a very narrow range of values to a much broader range of values, which suggests that changes in how land and resources were utilized on the Great Hungarian Plain affected incorporation of strontium into the skeletal system. This study indicates that the strontium isotope ratio is a valuable tool for identifying more subtle changes in prehistoric behavior such as a shift to a more pastoral economy.     

Copper quality and provenance in Middle Bronze Age I Byblos and Tell Arqa (Lebanon)

Forty-four Middle Bronze Age I weapons discovered at the sites of Byblos and Tell Arqa in Lebanon were investigated in order to study their copper quality and provenance. The evaluation of copper qualities is based on quantifying permanent inclusions such as copper sulfide and lead globules. The provenance of copper was studied using lead isotope analyses. For further discrimination between copper groups and sources elemental analyses by PIXE were performed on some of the weapons investigated. The results revealed two copper groups that could be qualified as “dirty” copper and “clean” copper. The former was used in most of the weapon types whereas the latter was reserved for items made of high-tin bronzes (>11 wt%) which underwent heavy hammering during the manufacturing process. Even though several potential copper sources were identified, the data point to Iran and Oman as the most probable areas of origin for the metal used in these weapons. These results contribute to the study of inter-regional exchange networks in the ancient Near East.     

IRON IN ANCIENT COPPER

Analysis of early copper-base artifacts invariably reveals traces of iron. Iron enters the copper during the smelting process and the level of iron in the metalwork is an indication of the smelting technology. In areas such as Western Europe where prehistoric slag heaps are absent even in the proximity of undoubted ancient mines, the iron content is low reinforcing the link between smelting technology and iron content. Very occasionally the iron content was deliberately encouraged and alloys containing between 30% and 50% of iron in copper were made, mainly for use in currency. These alloys are without modern parallel and their metallography and method of production are considered in some detail here.     

COPPER AND BRONZE DURING THE ENEOLITHIC AND EARLY BRONZE AGE: A METALLOGRAPHIC EXAMINATION OF AXES FROM THE NORTHALPINE REGION*

This paper presents the results of a metallographic examination of Eneolithic and Early Bronze Age axes from the Northalpine region of central Europe. During this period, different types of copper were in use: arsenical copper, Fahlerz copper and tin bronze. We examine if and to what extent the different properties of the metals used were known to prehistoric metalworkers and actively manipulated in the production of the axes. The development of methods of casting and smithing is discussed. Both aspects contribute to our understanding of the nature of prehistoric technological change. During the Early Bronze Age of the Northalpine region, different traditions of early metallurgy can be identified, which differ in their use of Fahlerz copper, their attitude towards tin alloying and the use made of tin bronze in the production of the axes. These traditions can only be adequately described by reference to both composition—that is, access to different types of copper as well as tin—and knowledge of the production techniques provided by metallographic data.     

Evaluation of Fe isotope values as a provenance tool for chert artefacts from the north-eastern United States

Iron (Fe) isotope compositions of prehistoric stone tools and geological sources were compared to evaluate the robustness of this isotopic fingerprinting technique. Artefacts and source materials were collected from the Hatch site in central Pennsylvania, United States, where both veined chert (Bald Eagle chert) and stone tools coexist within several metres. Yellow artefacts (δ⁵⁶Fe = 0.38 ± 0.1, n = 7) and source materials (δ⁵⁶Fe = 0.42 ± 0.1, n = 8) isotopically matched within error. The source values also overlap yellow chert samples from three other Bald Eagle chert locations in the area. These values are different from six other chert locations in the north-eastern United States. These data suggest that the Fe isotope composition of chert artefacts reflect distinct geological sources. To enhance the mechanical characteristics of the stone tools, the chert experienced heat treatment, which induced a phase shift of the Fe oxide mineral goethite to hematite. This phase shift changes the colour of the chert to red. The red chert artefacts and source material also have overlapping Fe isotope values, but are 0.2‰ higher than the initial yellow chert. Experimental work where cherts were heated with different clays shows that Fe exchange with site soils induces the +0.2 fractionation. These data demonstrate that predictable Fe isotope fractionation occurs during heating, resulting in isotopically distinct artefacts.