Lot of variance in Khoisan ancestry in South African Bantus - Tswana have the most (~20%), Tsonga the least (~1.5%). Khoisan ancestry is always entirely from women. nature.com
Khoisan admixture in South African Bantus began in late 1st millennium AD. Tsonga & Venda mixed with Khoisan the earliest, supporting that their ancestors were among the earliest surviving Bantus in South Africa.
Greater & more recent Khoisan ancestry in Tswanas probably is due to the 17th & 18th century trends in militarization & centralization. Khoisan women, who are about a third of Tswana matrilines, were presumably enslaved in considerable numbers.
Interesting read on the relationship of Khoisan with Tswana and Boers in 19th & 20th centuries. Authoress says Khoisan would handle cattle raising & milking for their patrons, as well as some hunting. Khoisan could leave if they wanted. jstor.org
Loading suggestions...