Here there are only some Africans and Asians. Non?
Duo has browbeat you into putting "some" for "des". It's sad, but it's usually not correct. "Des" in this sentence is only the plural of "un/une". There is no direct counterpart in English. https://www.thoughtco.com/du-de-la-des-1368977
Why not il n'y a que?
It is accepted as "Ici, il n'y a que des Africains et des Asiatiques", or the same sentence with "ici" at the end.
Asiatics is OK in English l think, but not accepted
the adverb "here" can actually come at the beginning or elsewhere, isn´t it?