Suggestions for a Swahili civ:
Spawn: 900 AD, as InsanelyApple said
UP: Power of the Swahili Coast (or the Swahili Trade Confederation)
+2 trade routes in every city on the Swahili coast (Mogadishu to the tile 1E of the cow, South Africa)
UB: Dallal (replaces Customs House)
Available with Currency
Could use any sort of remotely unique Middle Eastern building graphic
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These were Islamic brokers commonly found on the East African coast, speeding transactions between merchants and acting as a translator and mediator between parties.
UU: Dhow (replaces Galley)
5 (or 6) movement speed, can travel through cape
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This is really the only option I can think of. It could replace galleys or triremes, but they were used for transport so I figure galley works best.
UHV:
1 - Have contact and open borders with 5 Islamic civilizations in 1250 (Arabia or Egypt, Moors, Mali, Mughals, 1 convert, if you're lucky both Arabs and Fatimids will be around)
2 - Have the highest commerce rate in the world in 1400 (maybe unfeasible?)
3 - Have 2 vassal states in 1500