Blemmyas from the Nurenburg Chronicle of 1493

THE BLEMMYAI or STERNOPHTHALMOI "chest-eyes" were a tribe of African or Indian men, without heads, whose faces were set upon their chests.

The Chest-Eyes were very popular in Medieval bestiaries and map illustrations filling the Terra Incognita.

Herodotus, Histories 4. 191. 3 (trans. Godley) (Greek historian C5th B.C.) :
"For the eastern region of Libya [i.e. North Africa], which the nomads inhabit, is low-lying and sandy as far as the Triton river; but the land west of this, where the farmers live, is exceedingly mountainous and wooded and full of wild beasts. In that country are the huge snakes and the lions, and the elephants and bears and asps, the horned asses, the Dog-Headed (kynokephaloi) and the Headless (akephaloi) men that have their eyes in their chests, as the Libyans say, and the wild men and women, besides many other creatures not fabulous."

Pliny the Elder, Natural History 7. 23 (trans. Rackham) (Roman encyclopedia C1st A.D.) :
"Ctesias [Greek historian C4th B.C.] writes that . . . westward from these [the Troglodytoi or cave-dwellers of the African Red Sea] there are some people without necks, having eyes in their shoulders."

Sources:

• Herodotus, Histories - Greek History C5th B.C.
• Pliny the Elder, Natural History - Latin Encyclopedia C1st A.D.