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Some of the most notable and largely endangered archaeological remains from the Lake Chad area consist of the ruins of fired-brick elite constructions connected to the Kanem-Borno Empire (ca. eighth–nineteenth century AD). In the course of the last 200 years, several of the elite structures known west of the lake were destroyed as a consequence of war, later having their fired-bricks looted for constructions elsewhere. One of the largest and most thoroughly plundered of those structures once stood within the walled settlement of Garumele, SW Niger Republic. In the scope of an experimental field study at that location and with a view to future work at related sites, we demonstrate that it is still possible to retrace the ground plans of Kanem-Borno fired-brick structures, even if these have been already completely pillaged. In addition, we present new chronological evidence suggesting that Garumele—as a walled urban settlement—was founded sometime between the mid-fifteenth and mid-seventeenth centuries, but most probably between the late sixteenth to mid-seventeenth centuries AD.  相似文献   
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In this paper, we present a model of prehistoric southwestern Colorado maize productivity. The model is based on a tree-ring reconstruction of water-year precipitation for Mesa Verde for the period A.D. 480 to 2011. Correlation of historic Mesa Verde precipitation with historic precipitation at 11 other weather stations enabled the construction of an elevation-dependent precipitation function. Prehistoric water-year precipitation values for Mesa Verde together with the elevation-dependent precipitation function allowed construction of the elevation of southwest Colorado precipitation contours for each year since A.D. 480, including the 30-cm contour, which represents the minimum amount of precipitation necessary for the production of maize and the 50-cm contour, which represents the optimum amount of precipitation necessary for the production of maize. In this paper, calculations of prehistoric maize productivity and field life for any specific elevation are also demonstrated. These calculations were performed using organic nitrogen measurements made on seven southwestern Colorado soil groups together with values of reconstructed water-year precipitation and estimations of the organic nitrogen mineralization rate.  相似文献   
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