Peter C.H. Chiu, An Historical Study of Nestorian Christianity in the T'ang dynasty between A.D. 636 - 845 (Ph.D. diss., Southwestern Baptist Theological Seminary, 1987)
In A.D. 635, when the political climate and other factors were suitable, Ta-ch'in-ching-chiao the Church of Assyria, or the Nestorian Church as traditionally called, came to China. Through the Silk Road, it reached Ch'ang-an, the capital of T'ang China with a group of pioneer missionaries that were headed by Alopen. Ta-ch'in-ching-chiao enjoyed prosperous days under the reign of T'ang T'ai-tsung and his son, Kao-tsung. After a setback in the time of Empress Wu, it had a revival in the reign of Hsuang-tsung. The religion survived the criticism of the Buddhists and Taoists; it struggled to maintain its status of being patronized by the imperial house.
In due time, new missionaries and lay Christians of different professions, especially military advisers, continued coming to China from Persia. This effort resulted in spasmodic revivals of the Church. In A.D. 781, Ta-ch'in-ching-chiao erected its Monument, traditionally called the Nestorian Monument, in Ch'ang-an. From then on, information of the Church was scant. Some fragmented secular records say that the Church was seriously hurt by an edict issued in A.D. 845 which intended directly to terminate Buddhism. But the Church was not exempted from the blow and then began a rapid decline.
What Ta-ch'in-ching-chiao had left in T'ang China was not clear, but a monument and eight documents, or sutras were actually found in A.D. 1625, 1908 and 1943. From the monument and the documents, a set of sound basic tenets of Christian faith was found. Also these reveal a kind of practice that belonged uniquely to the Assyrian Church.
The monument was a masterpiece of its kind and a rich source of history. The sutras were difficult to read and understand particularly those composed before A.D. 650 since they are full of T'ang dialect while the later sutras, written around A.D. 780 demonstrated strong influence received from Buddhism and Taoism whether in the styles or the use of theological terms and thoughts.
Reasons for the decline of Ta-ch'in-ching-chiao have been sought, as well as answers basically related to cultural, social, political, religious, and theological aspects.