Iron Age sites in northern Botswana’s Okavango Delta 2: the Xaro sites in the Panhandle of the river-delta system

Abstract

ABSTRACT The Xaro sites are located in the Okavango Delta Panhandle of northwestern Botswana. All have an upper component with pottery identical to that made by nineteenth-century and current Mbukushu potters. Xaro 1 also has European glass beads for which cited historical documents provide calendar year dates of between 1850 and 1890. Other historical documents place the Xaro 1 Mbukushu settlement from the 1890s into the early twentieth century. All three Xaro Early Iron Age components have pottery motifs common at Tsodilo and Cubango sites on the basis of which a date range of the late sixth/early eighth centuries AD for Xaro 1 is most likely, while several pottery distinctions suggest a chronological separation within the same range for Xaro 2 and 3. Xaro Early Iron Age pottery has two unique features not discernible by the unaided eye but identified by microscopic optical petrography: 1) a red iron oxide veneer approximately two microns thick on outer surfaces; and 2) a variably thick post-deposition deposit of caliche derived from calcite suspended in Okavango water. A third uniqueness is an SEM estimated firing temperature of at least 1000˚C, much higher than the ±800˚C common for southern African vessels. Two Xaro burials provide aDNA data on Early Iron Age people in southern Africa; discriminant analysis of multiple variables determined that no present-day population sampled so far has the same ancestry mix, probably reflecting a northern genetic influence and offering genetic support to the hypothesis of a pre-Bantu expansion of pastoralists into southern Africa.