Dioceses of the Church of the East, 1318–1552
The Dioceses of the Church of the East, 1318–1552 were far fewer in number than during the period of the Church's greatest expansion in the tenth century. Between 1318 and 1552, the geographical horizons of the Church of the East, which had once stretched from Egypt to China, narrowed drastically. By 1552, with the exception of a number of East Syrian communities in India, the Eccesiastical jurisdiction of the Church of the East was confined to its original heartland in northern Mesopotamia.
Background
Consolidation of East Syrian Christianity in northern Mesopotamia
By the end of the thirteenth century, although isolated East Syrian outposts persisted to the southeast of the Great Zab, the districts of northern Mesopotamia included in the metropolitan provinces of Mosul and Nisibis were clearly regarded as the heartland of the Church of the East. When the monks Bar Sawma and Marcos (the future patriarch Yahballaha III) arrived in Mesopotamia from China in the late 1270s, they visited several East Syrian monasteries and churches:
