Liberia became independent in 1847 and was ruled by descendants of American slaves until 1980 (a tiny minority of the population). Currently it seems to have the lowest per capita GDP of any West African country. Of course the civil war did not help.
That’s right - and if you look up the roots of the civil war, you’ll see that the “Americo-Liberians” basically subjugated the native West Africans (who overthrew them in said civil war).