Its main centres were at Edessa and Nisibis, but it was the literary language of practically all the Christian writers in the region east of Antioch, as well as of the Christian subjects of the Persian empire.
The site of Nisibis, on the great road between the Tigris and the Mediterranean, and commanding alike the mountain country to the north and the then fertile plain to the south, gave it an importance which began during the Assyrian period and continued under the Seleucid empire.
Ceded to the Parthians by Hadrian, it became a Roman colony (Septimia Colonia Nisibis) under Septimius Severus.
Nisibis early became the seat of a Jacobite bishop and of a Nestorian metropolitan, and under the Arabs (when it continued to flourish and became the centre of the district of Diya`r Rebi`a) the population of the town and neighbourhood was still mostly Christian, and included numerous monasteries.
Arab geographers and travellers of the middle ages speak in high terms of the gardens of Nisibis, and the magnificent returns obtained by the agriculturist.