No worries. As Dahomey is on the list of nations to be added, it's still very relevant material
In that case here is something I think could be useful for the Empire of Oyo
Oyo starts with +15% vassal income, +10% manpower
1. Oyo Cavalry Tradition-We became an empire on the heels of our cavalry,through better training and a better ability to keep horses we have managed to make our army well known for the hooves of it's horses; this professional force must be maintained-There is general consensus that the source of many of Oyo's victories were cavalry, but I'm unsure how high a benefit it deserves in practice.
2. Defense of Tradition-Let others convert to Islam; we have our faith and will keep it-+10% discipline, +10% religious unity, this idea becomes the second Mali idea if Oyo converts-While the benefits look over the top Oyo does have to deal with muslim powers, and is a very likely target for expanding muslims, force conversion is an option so this idea is there to encourage the ai and player to stick to the pagan faith. Just one of the +10% bonuses is roughly equivalent to other NIs, so if Oyo wants two for one idea it has to do what the idea says.
3. Quest to unify our culture-The Oyo Empire was the closest to unification the Yoruba ever achieved, can you do better?-Free CB against anyone occupying Yoruba culture territory.
4. Trans Atlantic Slave Trade-Same as Dahomey
5. Dynastic Reforms-On return from exile the Yaruba Dynasty busted anarchy and centralized the state allowing further expansion-+10% tax, -5% mercenary cost
6. Yoruba Craftsmanship-From our bronze sculpture to simple terracotta and stone our culture thrives thanks to the common craftsman who produce the regions best ironwork, and artwork to be proud of--10% stability +10% tax income
7. Yoruba Imperialism-We know how best to deal with those who fail to defend themselves; if they have a working structure why destroy it when we could tax it? +25% vassal income-Yoruba got a lot of it's income not only from taxation but from vassals; this should do a good job of encouraging an Oyo player to vassalize instead of annex.
Oyo gets the same benefit for all it's ideas that Dahomey does in order to give it a chance at diplomacy in order to simulate the fact that the Empire of Oyo was not colonized during the EU time period.