India was overtaken by its erstwhile ally East Africa in the 2110s for a variety of reasons (more proximate control of the space elevator, Pakistan & China throwing their weight against India, the Laccadive Crisis, India's birth rates plummeting faster, androvirus) and was promptly top dog up until 2146. Indonesia, Ethiopia, Mozambique, Angola and Brazil were all dismembered to some extent by then - with the creation of the Lei Lines the (relative) monopoly on space was blown wide open and East Africa tried rather futilely to stem the tide. The other four nations (Ethiopia never really recovered) promptly took the opportunity to hammer it into the ground and divide up the pieces.OK, what happened with Mombasa?
On a more Doylist level - East Africa invariably unites in the FH maps, because people think they've found something clever and reasonably likely (they have) and then just assume it stays that way - it's like how South Sudan's (few year old) borders are carved in stone as some sign of "modernity". An East African union wouldn't necessarily horribly overreach and get ganged up on by its neighbors, but I doubt the history of the next two-hundred years is just going to be that of present trends continuing indefinitely.