There is an interesting incidental remark by Lorenzo Valla, Italian scholar writing in the 1430s, where in a critical rejoinder to recently published theories on the supposed hierarchy of colour symbolism, Valla says
In my opinion, Ethiopians are more beautiful than Indians, for the very reason that they are blacker
[Et mea sententia Aethiopes Indis pulchriores, eo ipso quod nigriores sunt]
Leaving aside his opinion, and the issue of pure versus mixed colour values, this sentence, dropped in an example or analogy, seems to indicate [a] that ‘Ethiopian’ was in general, or at least learned use, as a term for Africans, or possibly anyone with a very dark skin; and [b] that both ‘Africans’ and ‘Indians’ were sufficiently familiar in Italy for Valla to assume his contemporaries would instantly understand his point.
Born in Rome around 1407, Valla had a rather peripatetic career owing to his critical opinions on papal power and in the mid-1440s left Italy first for Barcelona and then for Naples, before being welcomed back to Rome and appointed apostolic secretary by a new pope. So Valla could have been familiar with ‘Ethiopians’ in Spain or Italy. But equally interesting is the fact that Valla’s patron during his wandering years was Alfonso V of Aragon and Naples, who as well as being a fairly aggressive ruler was a patron of the arts and a keen classicist, also had active diplomatic relations with the kingdom of Ethiopia. According to Wikipedia, in 1428 Yeshaq I, ruler of Ethiopia, sent two envoys to Alfonso proposing an alliance against the Muslim forces, to be sealed by the marriage of Pedro, youngest prince of Aragon, to Yeshaq’s daughter – and requesting that neapolitan artisans be sent to Ethiopia as part of this deal. The thirteen craftsmen despatched by Alfonso perished en route; several years later Alfonso wrote offering the new emperor Zara Yaqob another team of craftsmen if their safe arrival could be guaranteed, but, says Wikipedia, this letter probably never reached Ethiopia.
Ethiopia was of course a Christian realm in Africa that the Western church was well aware of – and the relationship with Alfonso V may indicate that Valla, who may have met Yeshaq's ambassadors, meant ‘Ethiopians’ literally, not as shorthand for Africans.
As it happens, there are portraits of two of Yeshaq's successors in the Uffizi, Florence, painted about a century after Valla's remark (the Uffizi works are careful, almost contempoary copies). One is Lebna Dengel [aka Dawit II] who in 1520, according to Portuguese traveller Francisco Alvares, was
'a young man, not very black. His complexion might be chestnut or bay, not very dark in colour: he is very much a man of breeding, of middling stature; they said he was twenty-three years of age and he looks that. His face is round, the eyes large, the nose high in the middle and his beard is beginning to grow. In presence and state he fully looks like the great lord that he is.'
described on the panel: ATANADI ∙ DINGHIL ∙ MAGNUS ∙ ABYSSINORUM ∙ REX/ VVLGO ∙ PRETEIANES APELLATUS ∙ 1532 [Atanadi Dinghil the Great King of the Abyssinians/ Called Preteianes by the People 1532
It is not clear where the likeness of Lebna Dengal was drawn from; Paolo Giovio, who commissioned the whole series of famous men to which this work belongs, is known to have written all over Europe and the near East soliciting portraits, so it is possible it is based on a drawing, though it looks as if confected in accordance with contemporary portraiture with some reference to Alvares' description. The second Uffizi work labelled as an Ethiopian emperor is that of Alchitrof, which seems more or less completely fictive, even if the physiognomy depicted is recognisably 'African'. it would be interesting to discover who the original artist and patron thought the sitter to represent, and what the empty frame he holds was intended to signify.