Mar Sabor and Mar Proth
Mar Sabor and Mar Proth, according to Syrian Malabar Christian tradition, were two Chaldean Assyrian bishops who landed in the port of Kollam (in present-day Kerala) by the help of a Nestorian merchant, Sabr Iso in 823 AD. This was accompanied by the second Assyrian migration to Kerala. Many Syrian Christian families most notably the Muthalaly family of Kollam, Panicker family of Kundara, Vaidyan family of Thevalakkara and the Tharakans of Kollam are descended from these migrants. The mission is said to have received permission from the then king of Kerala to build a  church in Kollam. That the historicity of this mission cannot be verified does not dispute the epigraphical evidence that Christians were on the Malabar Coast in 9th century AD. Kollam Syrian copper plates, a 9th-century royal grant from Kerala, mentions that certain Maruvan Sapir Iso built a church at Kollam with the blessing of the then Emperor of Kerala. It is likely that Mar Sapir had a companion named Mar Prot. A stone cross, one of the five Persian Crosses, with Sassanid Pahlavi inscription recovered also mentions certain "Afras the Syrian" as "the son of Chaharabukht". The two  bishops are said to have died in Kerala and have been considered as saints by the Saint Thomas Christians. Veneration. Sabor and Aproth were highly venerated in India among the Saint Thomas Christian community. A number of churches including Kottakkavu, Udayamperur, Kayamkulam, Kollam and Kothanallur, were dedicated to these saints. MS Vatican Syriac N. iv., which is dated to 1556 and written in the Kottakkavu Kandīshā Church, has the following colophon in folio 278: Variations of the names. "Mar" is a Syriac term meaning 'Saint' Synod of Diamper. When they arrived on the Malabar Coast, the Portuguese noted at least  78 extant church communities closely interwoven with the local community in different parts of Kerala. Quilon, Angamaly, Kaduthuruthy and Cranganore (now known as Kodungallur) had the largest population of Saint Thomas Christians in Kerala. Giovanni Empoli, who came to Quilon in 1503, estimated that there were more than three thousand St. Thomas Christians in Quilon alone. After 1561, Thomas Christians were branded heretics by the Goa Inquisition. The infamous Synod of Diamper (1599) anathematized all Christians of India who did not submit to Rome. The synod even branded Mar Sabor and Mar Prot as "Nestorian heretics" at the instance of  the Portuguese.