Are you referring to Beta Israel, which established a kingdom in the Semien Mountains in the 4th century and survived in some form to the 17th? The country to which some sources tie Queen Judith/Gudit (who is referred to by others as a pagan)? If that's the case, it needs to be noted that there is very little information on this subject, much less than the broader topic of pre-modern Ethiopian history which is still full of holes and questions.
My point is, counter factual speculation serves no purpose if we are still speculating over the actual historical events.