If I go much further south, I'll be crowding East Africa, and Nigeria is more well known than some of the others, but I might. I'll give whoever's playing East Africa time to comment. However, regardless, my expansion will be kept to Sub-Saharan Africa, so we shouldn't crowd.
Kingdom of Benin (aka Nigeria)
The Kingdom of Benin was the greatest nation in the known world for years. Until a few hundred years ago, strange, pale-skinned men appeared off the coast on boats. They were from a place called Portugal. The Bini people came to find out about a whole land of independent, wealthy, and advanced nations all fighting for the top spot in the world. They traded with these "Portuguse" but before long other powers offered deals too. The most appealing was that of the English. For years, the Bini people saw ships come from the Northwest with exotic new goods and tools with the strange pale men, but never questioned why or where they came from. They just loaded up the local resources such as ivory and palm oil onto the ships to get the new technology from Europe. Sometimes, the traders would take people away too, often enemies of the state. What became of them, people were afraid to ask. Over time, it came to the leaders' attention that the European powers were encroaching more and more on Benin's soviergnty. Spies were sent to Europe to study how Europe worked in hopes of finding ways to make Benin more respectable to Europe. Slowly, Benin evolved to become more and more European-like. Yet England continued to try to take the land as her own. But in the late 1700's, Benin finally decided to expel all Europeans from the Kingdom. At this point, Benin was as advanced as some of the weaker European states, with growing industry and a slowly increasing middle class. Because of the attempts to mimic Europe, Benin was more advanced than any other state in the area, and they looked to exploit this advantage and spread influence. Soon, all the Niger River delta and a ways inland were under firm Benin control, with the capital of Lagos (originally Eko, but renamed in the Portuguse language) the center of it all.
Color: Whatever isn't used that looks aesthetic
Government: Very nationalistic and distrust of Europeans. Progressive.
Economy: Mainly traditional, but with growing industry and middle class.
Leader: King Lle-Ibinu
National Goals: Make Benin a nation rivaling European powers in terms of influence, economics, and developement. Keep the European powers in check, especially in Africa.