Dominicans are African because of mixing during the slave trade.
It's well documented that prior to colonization, the island of Hispaniola was comprised of Caribs, Arawak and Taino indians.
Eventually most of the native population was wiped out, so a lot of the current population has traces of black, indian (when I say Indian, I mean India/Middle East), and european ancestry.
And in the future would will see a lot of half Asian (Korean and Chinese for the most part), South Americans, A LOT of Italians etc... a lot of immigrants are working and living in DR