Nestorian Church. As such, the Church of the East accepts only the first two ecumenical councils of the undivided Church--the First Council of Nicaea and the First Council of Constantinople--as defining its faith tradition, and rapidly took a different course from other Eastern Christians.

The Church of the East spread widely through Persia and into Asia, being introduced to India by the 6th century and to the Mongols and China in the 7th century. It experienced periodic expansion until the 14th century, when the church was nearly destroyed