After several generations of immigration

Neither, or you won't be called Asians, and they won't be called Africans.

When you go to Africa, you may get a tan. First of all, you won't be as black as Africans. You will recover after you stop tanning.

The problem is that no one can guarantee that the descendants of several generations in Africa will not marry Africans, or that the descendants of blacks will not marry Europeans and Americans when they arrive in Europe and America. This is not feasible from a social or medical point of view.

You can ask your children to find Asians, and your children may find Asians again, but later, although the Asians that children and grandchildren find are all yellow-faced, it is hard to say that they are not mixed up.

As for blacks, they have married Europeans and Americans, and African blacks have different looks. The following two are hybrids. Imagine their descendants hundreds of years later, are they black, Hispanic or white?