This Christian sect that constituted a large part, maybe even the majority of Christians in Arabia and the Middle East during the time of Muhammad. This group was very missions oriented.

The Nestorians were equally active. They established schools in many towns. In their monasteries monks could be heard chanting their offices, so that the Arabs became accustomed to seeing the monks at pray day and night, prostrating themselves with their faces to the ground. In prayer the Christians turned to the east. Such men were a familiar sight on all the caravan routes of Arabia. The monastery at Hira was established by the Nestorians in the fifth century, and from thence Christianity was carried to Bahrayn. While Muhammad was a young man, King Nu'man of Hira was converted to Christianity. The church in the east was predominately Nestorian, though a fair number of Monophysites were to be found there. (Guillaume, "Islam", p. 15)

Professor Tore Andre, of the University of Upsala, has shown in his recent study of Christian origins of Islam ... that the opinion hitherto current, of sundry heretical sects to which Muhammad was indebted for his Christian ideas, is a mistaken one. He directs attention to the great church of Asia, the Nestorian Church, as the prime source of Christian thought and life in pre-Islamic Arabia. There are many points of simimlarity between Muslim teaching and Nestorian christianity, but the circle of ideas most prominent and characteristic, according to Tore Andre, is eschatology with its extraordinary stress on the day of Judgment. (Zwemer: Foreword to "Nestorian Missionary Enterprise" by J. Stewart, T. & T. Clark, 1928, p. 8) J.W. Sweetman believes that it can be shown conclusively that Arabia came into contact with all three major sections of the Church, i.e., the Byzantine, Nestorian and Jacobite-Monophysite churches (Islam, and Christan Theology. London: Lutterworth Presss, 1945, Vol. I, p. 2) However, it is important to note that it was the Nestorian Church which exercised the most I significant influence on Islam. In this connection J. Stewart informs us: Prior to A.D. 547 when the great Jacobite revival began, the only form of Christian faith known in the whole independant Arabia and Hirtha was that held by the "Church of the East," the so-called Nestorians, and it is practically certain that every presbyter and bishop in the whole of that area recognized and acknowledged allegiance to the patriarch of Seleucia. When therefore, mention is found of Christians in Mecca and Medina and even in the tribe of Koreish, one is warranted in assuming that all such, prior to at least, the middle of the sixth century, were in communion with the same patriarchate. When the suddenn rise of Islam took place it was the Nestorians who suffered most from the impact. (J. Stewart, op. cit., pp. 71, 72)

Islam did not arise in a backwater from some obscure Judaic-Christian sect, but arose in the full stream of religious life in Asia. (R. Bell, "Origins of Islam in Christian Environment", London: Macmillan & Co., 1926, p. 9)