Could have, would have, should have. You can, in theory, do a lot more. Not sure what the point is of discussing this.
Would make for a good fantasy manga.
Somali history freak, avid Somalispot Culture-History poaster, big Romanophile on the side, super ethnonationalist, wishes things were better.
He's at his desk lurking, wishing Somalis 2300 years ago decided to go Mongolian on Africa. He goes to sleep and wakes up as proto-Barbar, son of some semi-important city-state chief, at war with brotherly city-states. Uses his vast knowledge to first unite city-states and pastoral tribes and then conquer in whichever direction. South would be hardest to work with but proto-Maasai-Datoog types would be cool to war against; going north would be super cool, conquering a budding Aksum and into Meroe and soon enough Alexander. Maybe make it 2000ybp so big enemy at end of series would be Rome in Egypt.
Got carried away. Literally made him a self-insert. Reckon I'd be able to do it.