Background and Knowledge: On Quora I came across some pretty bad answers from people of Afrikaner nationalist mindset (their account having disparaging remarks on Bantu people) that basically framed Bantu's as "colonists" like the British (who are also disliked by Afrikaner Nationalists) that invaded South Africa, which was meant for "white people" and that they were given rights despite that.
The problem is that doing research on the matter from sources done during the Apartheid (many claim revisionism after) the anthropology at the time ( DW Phillipson for instance) has Iron Age cultures of the Bantu present in the Limpopo at the 11th century as a late date. Likewise, the early laws and commissions that pertained to Bantu were all referred to as "Native", so it's obvious an "immigrant" perspective wasn't the standard view. This seems to be due to conflating the Cape region, the southwest, with the Southeast. While Azania (another area disputed by the same types I'ved seen) wasn't always thought to be a Bantu areas, metallurgy Archaeology assoicates Bantu people with habitation in the area since 1000 A.D
Finally, the matter of how they came into the Union. This timeline indicates that, like the Boers, Zulu and Xhosa populations were integrated as a result of warfare. The Zulu for instance in 1897 were annexed into Natal, though i couldn't find specifics on the Xhosa outside of being defeated in warfare somewhat after that.
What I do know is that this doesn't line up with "mass immigration" like with the Mfecane, which was well before the Union. This dispersal was more consequential, according to this graph, the Xhosa were only peripheral to the migrations and were a border against the chaos. They were already adjacent to Cape colony prior to this.
The only "migration" that this could be speaking would be movements from Bantu reserve spaces to Urban white areas AFTER being annexed or absorbed and prior to Land Acts being inforced. The only instances that really comes to mind are the Urban populations prior to translocation, as the trend prior to 1913 was either Blacks owning their own land and expanding ownership or renting land from whites.
And on the issue of "rights", technically from what I've read the logic of reserves and relocation to Bantustans were argued to maintain self-rule for Bantus at the time, the reality was that with the multiple "Native laws" done by the government and the laws made around it the migration of wage labour of Bantus due their lands being poor for extensive farming that they were used to, there wasn't much effort at all following those laws to maintain "self rule". They were really only allowed to make their own laws for their own lands, but that overshadowed the greater imbalance of control between the local and larger government.
Question: Does contemporary literature on events and laws match with my impression of Bantus being annexed into the Union versus simply "migrating" and designated as such?
You are are referring to the 'vacant land' myth, which was actively propagated by the national party during the 20th century. Unsurprisingly, having learned it in schools, it continues to be a widely held belief among many white South Africans. It is false. For an overview of the myth, see Clifton Crais, "The Vacant Land: The Mythology of British Expansion in the Eastern Cape, South Africa," Journal of Social History 25:2 (1991).
The Xhosa, Zulu, and other Bantu-speaking African communities were living in South Africa for centuries (in some cases, many centuries) before white colonization. They were annexed through processes of violent conquest. For the Xhosa case, the Wikipedia entry for "Xhosa Wars" is reasonably good; for a longer treatment, you can look at Noel Mostert's Frontiers. For the history of the Xhosa before conquest, Jeff Peires's The House of Phalo remains the canonical text.
The exact facts of the Mfecane are the subject of intense historical debate, but even those historians who argue that the Mfecane did represent a substantial population movement would not claim that this movement was into otherwise vacant land.
The history of "native law" is complicated. As of 1910, "native law" was recognized in some parts of South Africa, but not all (primarily Natal, the Transkeian Territories in the Eastern Cape, and to a limited degree in the Transvaal). However, even in those areas, it is extremely important not to confuse recognition of "native law" with self-government. By the early 20th century, "Native law" was generally enforced in the courts of white magistrates, not in those of traditional leaders. Even where chiefly courts were recognized, they were subject to the authority of the white state; chiefs themselves were appointed by colonial administrators and could be fired. "Native law" itself was fundamentally transformed by colonial rule. British administrators could, and did, simply change it or add to it. More subtly, enforcement in colonial courts profoundly shifted the dynamics of the legal system, even when the "rules" appeared to remain the same.
If you're still interested, I'm happy to answer follow-up questions. I also recommend Robert Ross's A Concise History of South Africa for an introductory text that starts well before colonialism. Norman Etherington's The Great Treks focuses on the rise of the Zulu empire, but also provides a good overview of the precolonial polities that existed in the South African interior before colonial conquest.
