Analysis of information sources in references of the Wikipedia article "Amharic" in English language version.
The analysis of linguistic distributions suggests that the proto-Ethiopians of the third millennium B.C. spoke languages derived from a single stock, that is known as Hamito-Semitic or Afro-Asiatic. This ancestral language probably originated in the eastern Sahara, before the desiccation of that region... the homeland of Afro-Asiatic may have been in southwest Ethiopia. Wherever the origins of Afro-Asiatic, it seems clear that peoples speaking proto-Cushitic and proto-Omotic separated as groups with distinct languages by the fifth or fourth millennium BC and began peopling the Ethiopian plateaus not long after. Proto-Semitic separated at about the same time or somewhat earlier and passed over into Asia Minor... it seems reasonable to follow I. M. Diakonoff in assuming that the Semitic-speakers moved from the Sahara across the Nile Delta over Sinai, so that the presence of Semitic-speaking populations in Ethiopia must be attributed to a return movement of Semitic-speakers into Africa from South Arabia... As a base line for reconstructing the history of Greater Ethiopia, then, we may consider it plausible that by the end of the third millenium B.C. its main inhabitants were dark-skinned Caucasoid or "Afro-Mediterranean" peoples practicing rudimentary forms of agriculture and animal husbandry and speaking three branches of Afro-Asiatic – Semitic, Cushitic and Omotic.