Thomas Christians is the term often used for Christians in south-west India (Malabar) belonging to Churches of Syr. tradition, since they trace their origins back to St. Thomas who, according to tradition, arrived in South India in 52. The early name given to them locally was ‘Nazrani’, which corresponds to nāṣrāye, which was used by the Sasanian authorities for Christians (subsequently taken over in Arabic). Prior to the arrival of Europeans in the 16th cent. the Thomas Christians were all part of the Ch. of E. Since the late 16th cent., however, successive divisions have taken place, with the result that today in Kerala there are seven different Churches of Syriac tradition: those of the original E.-Syr. liturgical tradition are: the Malabar Catholic Church and the Chaldean Syrian Church (the latter belonging to the Ch. of E., and not the Chaldean Catholic Church); and of W.-Syr. liturgical tradition: the Malankara Syriac Orthodox Church, under the Patriarchate of Antioch; the independent Malankara Orthodox Syrian Church; the Malankara Catholic Church; the small Malabar Independent Syrian Church, and the reformed Mar Thoma Syrian Church.

Written and archaeological sources for the pre-Portuguese period are minimal, local written ones having been destroyed at the Synod of Diamper (Udayamperur, 1599). Sea trade between the Red Sea and the south Indian port of Muziris (usually identified as Kodungalur/ Cranganore) was well developed by the 1st cent. AD, and there is nothing impossible in the strong local oral and written traditions that St. Thomas came to south India (although the Syriac Acts of Thomas, of perhaps the 3rd cent., seem to bring him to the north). Several 3rd-cent. Greek sources, however, link him with Parthia. Ephrem refers to Thomas being killed in India, and states that a merchant had brought some of his bones to Edessa (madrāše of Nisibis 42.1–2). Mylapore as the site of Thomas’s martyrdom is not attested until the Middle Ages, in accounts by Western travellers (Shlemon of Baṣra, ‘Book of the Bee’, ed. Budge, 119 [tr. 105], knew a tradition that ‘he was buried at Maḥluph in the region of the Indians’). Much confusion has been caused, especially in Greek and Latin sources, by the ambiguity of the term ‘India’, which often clearly refers to Ethiopia or South Arabia.

It is unclear when the link with the Ch. of E., in the Persian Empire, was established. According to the Chronicle of Siirt ( [PO 26], I.8), Dodi, bp. of Baṣra (evidently 3rd/4th cent.) left his see to go to India where he converted many people; later (PO [117], II.9;) Maʿne, metropolitan of Fars (late 5th cent.), is said to have composed madrāše, memre, and ʿenyāne in (Middle) Persian for liturgical use and sent these books ‘to the islands of the sea and to India’. In the early 6th cent. Cosmas Indicopleustes, a friend of the Catholicos Mar Aba, speaks of a church at Male (Malabar) and a bp. ‘appointed from Persia’ at Kalliana (identified either as Kalyan, Mumbai-Pune area, or as Quilon; ‘Topography’, III.15), and in the mid-7th cent. one of Ishoʿyahb III’s Letters (ed. Duval, p.252) implies that India’s line of bishops was dependent on the metropolitan see of Rev Ardashir (in Fars, on the Persian Gulf). The link with Fars helps explain why Pahlavi, rather than Syriac, features on the various 9th-cent.(?) stone crosses (an improved reading for one of these is given by Ph. Gignoux, Studies in Honor of J. C.  Greenfield, ed. Z. Zevit et al. [1995], 411–22). One of Patr. Timotheos I’s lost letters was to the Indian Christians concerning the election of a bp., and elsewhere he speaks of monks regularly travelling to and from India.

Although India was supplied with bishops (and from Timotheos’s time, metropolitans) from the Middle East, the effective control lay in the hands of the indigenous Archdeacon.

References to two early migrations from the Middle East to Kerala are first recorded by 16th-cent. western writers, based on local oral accounts. The first migration is linked to Knai Thoman, represented in western sources as Thomas of Cana, the Canaanite (thus also in one Syriac text, Mingana 1926, 481, 513), who is said to have come with a group of Christians including a bp. Yawsep (sometimes, of Edessa) in 345. Numerous inconclusive attempts to explain the name Knai have been made. The tradition is especially important for the endogamous Knanaya (or ‘Southists’) who trace back their origins to this Thomas. A later group said to have come from the Middle East was led by two bishops, Mar Shabur and Mar Prot (Phrahat, or Peroz?), together with ‘the resplendent’ Sabrishoʿ; an exact date, 823, is even given in one Syriac source (ed. Land, Anecdota Syriaca, vol. 1, 27, tr. 125). This Sabrishoʿ is often identified with ‘Marovan Sapir Iso’, the builder of the Tharisa church in Quilon which was granted certain privileges in a set of copper plates in Old Tamil, dated 849.

The only pre-Portuguese Syriac document from India is a Lectionary of the Pauline Epistles, copied in Shengala (Cranganore) in June 1301, in the time of ‘the Turkish Catholicos Patriarch Yahbalaha V [!, in fact  III] and Metropolitan Mar Jacob, governor of the holy throne of Mar Thomas the Apostle’ (ms. Vat. Syr. 22); the scribe identifies himself as deacon Zkarya, aged 14.

A very important Syriac source from shortly after the arrival of the first Portuguese is a letter of 1504, with a historical introduction (ed. Assemani, BibOr, III.ii, 589–99; tr. in Mingana 1926, 468–73). This tells how in 1490 two Indians travelled to Gazarta (modern Cizre) to ask the cath. for bishops; two bishops were consecrated and sent to India, and then in 1501 the next Catholicos sent three further ones, who in 1504 dispatched back the letter in question, describing the situation of the Thomas Christians (‘some 30,000 households’). One of the two Indians in 1490 was ‘Joseph the Indian’ who later provided the account of Malabar that formed Book VI of Fracanzano da Montalboddo’s immensely popular Paesi novamente retrovati (1507). And one of the bishops consecrated in 1501 was Mar Yaʿqub who was to play a prominent and difficult role in dealing with the Portuguese; he died some time before 1554. A slightly later Syr. bp. was Mar Yawsep, consecrated for Malabar by the Chald. patr. in 1558 (five years after the separate Chald. Catholic line had come into being). Western missionaries in Bassein, however, were successful in preventing him from reaching his destined flock. While in Bassein, and even during his long sea voyages, he diligently copied Syriac mss., several of which survive (van der Ploeg 1983).

Although the Thomas Christians had at first welcomed the arrival of fellow Christians from Europe, by the end of the 16th cent. the situation had changed. The last Indian bp., Mar Abraham, died in 1597, and in 1599 the metropolitan see of Angamali was demoted to a bishopric under the archbishop of Goa. The next year the Malabar Church was put under the Portuguese Royal Patronage (Padroado). The destruction of all Syriac books considered heretical at the Synod of Diamper (1599) and the Romanization of the rite (though Syriac was still allowed) witness to the domineering character of the European hierarchy in India. Any attempts to contact bishops — even Chald. Catholic ones — in the Middle East were foiled. In the end, (false) rumors of the drowning of a bp. from the Middle East, Mar Atallah, led to open revolt in 1653, with the ‘Oath of the Coonan Cross’ (Mattancherry), when the Archdeacon Thomas was ‘ordained’ as bp. by 12 priests, claiming to have a letter from Mar Atallah legitimizing this. This effectively split the Thomas Christians into two nearly equal halves, those who remained under the control of Rome, and those who were in due course to come under the jurisdiction of the Patriarchate of Antioch.

Contact in due course was made by the adherents of Thomas with a Syr. Orth. bp., Mar Gregorios, in 1665, and links with the Syr. Orth. Church were further strengthened in 1685, when Maphrian Baselios Yaldo and Mar Ivanios were sent to India by Patr. ʿAbdulmasīḥ I; although Mar Baselios died shortly afterwards, he left a great impression (thus at Kothamangalam a long inscription in his honor was put up in 1874). In this way the W.-Syr. liturgical tradition (and script) was gradually introduced into Malabar, and seems to have been fully effected by the end of the first quarter of the 19th cent. (van der Ploeg 1983, 39). Prior to this, in 1772, a quarrel had led to schism and the establishment of the separate small Malabar Independent Syrian Church, based in Thozhiyur.

Further divisions came in the 19th cent., when a reform movement among the Syr. Orth., led by Abraham malpan and supported by Anglican missionaries, led to the emergence of the Mar Thoma Church, which formally came into being in 1888. The second half of the 19th cent. also witnessed the renewal, after a break of some 400 years, of the ancient link with the Ch. of E., with the emergence of the Chaldean Syrian Church.

Towards the end of the 19th cent. requests began to be made by the Syr. Orth. to the patr. of Antioch that a cath. (corresponding in rank to that of the earlier Maphrian) be appointed for India. Patr. Peṭros IV (III) agreed to consider the matter, but nothing was done until the deposed Patr. ʿAbdulmasīḥ II visited India in 1912 and consecrated Pawlos Mar Ivanios as cath. , an action which effected a schism with the party loyal to Patr. ʿAbdullāh II. Though a re-unification of the two sides was achieved in 1964, the break was renewed in 1975. Drawn-out and expensive litigation over property remains a running scandal.

A different division within the W.-Syr. tradition took place in 1930, when Mar Ivanios, together with a sizable group of Syr. Orth., entered into communion with Rome, thus marking the beginnings of the Malankara Catholic Church. In the E.-Syr. tradition one further division took place in 1968, just within the Chaldean Syrian Church, when loyalties became divided between the two Patriarchs, Mar Shemʿon (New Calendarists) and Mar Darmo (Old Calendarists), leading to the establishment, from 1971, of two rival metropolitans in Kerala. This schism, however, was successfully healed in 1995, when the entire Chaldean Syrian Church was united with Patr. Mar Denḥa IV (New Calendarists).

Syriac remained the language of the liturgy until well into the 20th cent. in most of the Churches of Syriac tradition; today, however, it has almost entirely been replaced by Malayalam, even among the Syr. Orth. where it has held out longest. A large number of Syriac mss. have been copied in Kerala (van der Ploeg). Less frequent has been the use of Syriac for inscriptions, the earliest being dated 1575 (Mulanthuruthy); in more recent times it has principally been the Syr. Orth. who have retained Syriac for funerary and commemorative inscriptions; an impetus to this practice seems to have been given by Mar Kurillos Yuyaqim, from Ḥbob in Ṭur ʿAbdin, who came to Malabar in 1846, where he died in 1875. A Corpus of Syriac inscriptions in Kerala, by F. Briquel Chatonnet, A. Desreumaux, and J. Thekeparampil, has recently been published. During the second half of the 19th and well into the 20th cent. a number of Syriac printing presses were functioning; particularly important ones were the St. Joseph Press, Mannanam (for E. Syr.), and the Mar Julius Press, Pampakuda (for W. Syr.).

See Fig. 64, 65, 66, 116, 117, 118, and 119 .