Provenance and reference groups of African Red Slip ware based on statistical analysis of chemical data and REE

African Red Slip (ARS) ware (sigillata africana) from three archaeological sites in northern (Oudhna, Sidi Khalifa) and central Tunisia (Henchir el Guellel) was studied by X-ray fluorescence and statistical treatment of chemical data in order to define homogeneous reference groups. The specimens from Henchir el Guellel are clearly different from those of the other two sites, which are compositionally more similar, due to their geographical vicinity. ARS ware from Sidi Khalifa is chemically very homogeneous, whereas that from Oudhna clusters into two distinct groups. The chemical correspondence with literature reference groups, based on both kiln wastes and sherds from archaeological surveys, defines new reference groups, statistically more numerous and representative. Comparisons of chemical data by neutron activation analysis on selected potsherds and clays from the surroundings of each site also identified the probable base-clays used to produce the ARS ware of Oudhna, Sidi Khalifa, and to advance some hypothesis on that used in Henchir el Guellel, thereby overcoming difficulties in assessing chemical contents of elements due to levigation processes.