Also check national constitutions for specific protection the rights of indigenous peoples
Some specialist law journals which may be particularly useful for this topic:
Finding books on this topic
SOLO searches will probably reveal that other parts of the Bodleian - such as the
Bodleian Social Science Library
Bodleian Social and Cultural Anthropology Library
and the Bodleian Closed Stacks
also have useful texts on this topic.
Don't be too specific with your geographic element in the subject searches - try Africa, Southern & Africa to find relevant chapters
Indigenous peoples -- Legal status, laws, etc. -- [geographic unit]
Indigenous peoples -- Civil rights -- [geographic unit]
Indigenous peoples -- Land tenure -- [geographic unit]
Please ask a member of staff for directions as books are likely to be in at least 3 different sections of the LawBod with shelf marks beginning eg S. Africa, Internat and/or General.
Land, power & custom : controversies generated by South Africa's Communal Land Rights Act by African Studies collection held by the Bodleian Social Science Library
You may well find that your SOLO searches find useful titles in the Bodleian Social Science Library. Your Oxford University or Bodleian Reader's Card gives you access to this Library - and luckily it is just next door!
Indigenousness in Africa : a contested legal framework for empowerment of 'marginalized' communities by 
Land Rights of Indigenous Peoples in Africa by Open Access books available as free downloads to all with access to the internet
The climate change regulatory framework and indigenous peoples’ lands in Africa: Human rights implications by Perspectives on the rights of minorities and indigenous peoples in Africa by