See J. Joseph, The Nestorians and Their Muslim Neighbors (1961); W. C. Emhardt and G. M. Lamsa, The Oldest Christian People (1926, repr. 1970); N. Garsoian and T. Mathews, ed., East of Byzantium (1982).
For many generations until the 16th century, the Christians of India were accustomed to receive their bishops from the Church of the East. Following the Portuguese colonization of several coastal regions of India, Christians in Malabar were allied with the Roman Catholic Church. Beginning in the 17th century, ecclesiastically conservative groups began to seek leadership from the Syrian Orthodox Church.
The modern history of the Church of the East in India dates to the decades after 1814 when leading Christians in Thrissur, failing in their own attempt to gain a bishop from the Syrian Orthodox Church, began to seek to have a bishop ordained by the Catholicos Patriarch of the Church of the East in Qochanis. The priest Anthony Thondonatta was consecrated bishop as Mar Abdisho in 1862 in Qochanis, though he did not begin functioning as Metropolitan in India until 1882. Their publishing arm, Mar Narsai Press, prints several liturgcal books used throughout the Assyrian (often considered "Nestorian") Church of the East. The present Metropolitan, Mar Aprem Mooken (ordained in 1968), is headquartered in Trichur and is a noted author. Marth Mariyam Cathedral is the seat of the Metropolitan.