Starting from 1176, have both the papacy and the Catholic European Kingdoms have a more favorable view of Ethiopia when they eventually discover it. In OTL, there was this "prester John" myth and for awhile the Portuguese thought Ethiopia was the same, but relations eventually turned frosty because of the religious differences between the Ethiopian Orthodox Church and the Catholic Portuguese. One way to do this is have some POD resolve the East-West split and come to embrace all forms of Christianity. The challenge is to find a POD that would make Catholic Europe view Ethiopia a bit more favroably without making them tolerate the East any more than OTL. It doesn't need to be anything as strong as generations of intermarriage. For example, England has had conflicts with Scotland, Castile, and the Holy Roman Empire before, but at times had cordial relations with them, something they did not do with Cordoba.