Comment on The World Turn'd Upside Down by Kurarun
The allied native kingdoms are already protectorates - they're technically independent, but their foreign policy is totally under the control of the United Provinces. Post-decolonisation I can see Basutoland joining with whatever country succeeds the United Provinces, but I can't really see the others being absorbed before or after decolonisation. 
Okay, that makes more sense than Europeans actually leaving the natives alone. They were just nicer about it here. Wait did you mention anything decolonization in the discription? If not what causes that to happen? It is a relatively plentiful region. It sound like they have it pretty good there.
I'm not exactly sure what causes decolonisation in this timeline, but I'm imagining it as being similar to our timeline - economic and political chaos following wars in Europe, combined with increased resistance and nationalist sentiment from the population of the colonies.