κέγχρος, ό – millet (panicum miliaceum), anything of small grains like fish roe
The earliest reference to drinks made with barley is found in Hecataeus (ca. 550-476 BCE). He describes a drink (παραβίην) among the Paeonians (a region to the north of Greece). Nelson notes in his review of ancient Greek and Roman beer that millet is largely found among Africa or the regions to the north of Greece (Paeonia, Pannonia, and Scythia) (Nelson 2001, 97).
Millet is best grown in semi-dry climates. Proso millet (κέγχρος) is typically used as bird seed in the US, but it still is harvested for food in certain parts of Asia. It seems that this variety of millet is no longer grown in Africa (261-263).
Nelson, M. 2001. “Beer in Greco-Roman Antiquity.” Ph.D. dissertation, The University of British Columbia.
Board on Science and Technology for International Development, 1996. Lost Crops of Africa. Volume 1. National Academy Press.
Wikimedia Commons, Isidre Blanc