During the Middle Ages, the Eritrea region was known as Medri Bahri ("sea-land"). The name Eritrea is derived from the ancient Greek name for Red Sea (Ἐρυθρὰ Θάλασσα Erythra Thalassa, based on the adjective ἐρυθρός erythros "red"). It was first formally adopted in 1890, with the formation of Italian Eritrea (Colonia Eritrea). The territory became the Eritrea Governorate within Italian East Africa in 1936. Eritrea was annexed by Ethiopia in 1953 (nominally within a federation until 1962) and an Eritrean Liberation Front formed in 1960. Eritrea gained independence following the 1993 referendum, and the name of the new state was defined as State of Eritrea in the 1997 constitution.[citation needed]

What was the Eritrean region known as during the Middle Ages?