The reason Somalis and other Horners don't identify as Black is due to geography. Due to the highlands in Ethiopia, we had virtually no extensive contact with the rest of Africa outside the Horn. Even Somali presence in Kenya is very recent. We have much more in common with Yemen than Cameroon.
Hell, Somalis have had more contact and influence with India and Indonesia than Nigeria and Angola.
Hell, Somalis have had more contact and influence with India and Indonesia than Nigeria and Angola.