Wikipedia:BorgiaMap page gives this detail,
The Borgia map includes a legend referring to Ebinichibel, who is described as "the Saracen Ethiopian king with his dog-headed people".
Is this related to any historical/legendary figure?
I don't know of any Ethiopians who ruled Saracens or vice versa, except Abraha of Axumite Kingdom who ruled a small portion of Yemen for a brief period.
Searching this term just gives links to the same map with the same detail.