(on sui juris churches in general)
Liturgical Family: Chaldean
Primary Liturgical Languages: Syriac and Malayalam.
Juridical Status: Major Archiepiscopal
Approximate Population: 4 to 5 million
Brief History: The Mar Thoma Nasrani or St. Thomas Christian community of India is very old. By their own traditions, they were founded by no less than St. Thomas the Apostle, who is said to have taken a missionary journey to India and been martyred in Mylapore in the Indian state of Tamil Nadu. It's not an impossibility; trade routes would have made it possible, and it is well established that there were already Jewish communities in the area. The earliest written account we have of St. Thomas the Apostle going to India, the Acts of Thomas, goes back to the third century. It is sometimes suggested that the Mar Thoma communities were founded by someone from a later generation who was also named Thomas; and indeed there are legends of a Thomas of Cana who brought Christians to the shores of India in the fourth century or so. Regardless, it is one of the ancient churches of the world, and even if it wasn't actually founded by St. Thomas the Apostle, for practical purposes it might as well have been. The Syro-Malabar Catholic Church is the lion's share of this community, being easily larger than its non-Catholic counterparts, which is one of the distinctive features of this Eastern Catholic church: it is the primary bearer of its tradition. It is also the third largest particular church in the Catholic communion, after the Latin and the Ukrainian churches.
To get to the Roman Empire from India, of course, would for the most part have required crossing the Persian Empire; it is thus not surprising that the Mar Thoma Christians historically have tended to be linked with the Church of the East, which was the primary Christian presence in Persia. This is simply a matter of geography; the Mar Thoma community seems to have had nothing to do with, and may indeed have had no knowledge of, any of the events that led to the split between the Catholic Orthodox in the Roman Empire and the Church of the East in the Persian Empire. Nonetheless, for well over a millenium, the Mar Thoma Christians belonged to the communion of the Church of the East, and it is because of this that they are East Syriac or Chaldean in their liturgy. But their customs and devotional life, of course, were undeniably Indian.
As the fifteenth century drew to a close, however, an event happened that would change the cultural landscape of India forever: in 1498, Vasco de Gama sailed into Calcutta. The Portuguese had arrived, casting out their far-flung trading net. This led to certain complications, as the Portuguese had difficulty understanding these Christians of the Malabar Coast, and tried to impose the Latin Rite. This led to the splitting of the Mar Thoma community, as parts Latinized and others did not, and the struggle for control became intense in the seventeenth century. Some Mar Thoma Christians cooperated with the Portuguese in latinization of their rite; these are the root of the Syro-Malabar Catholic Church. Others linked up with the Syriac Orthodox Church out of Antioch; these became the root for the Malankara Orthodox Church. Yet others intensified ties with the Assyrian Church of the East.
In 1778, however, two members of the Catholic community, Joseph Kariattil and Paremmakkal Thomma Kathanar, traveled to Rome in order to petition for some independence on the part of their St. Thomas Christians. This they received. This breathing room for cultivation of their heritage would slowly build as the Syro-Malabar Church received first eparchial status in 1887 and then Metropolitan status in 1923. During the Metropolitan phase, the church actually existed in two parts, headed by the metropolitan archbishops of Ernakulam and Changanacherry, but in 1992, John Paul II raised the status of the church to Major Archiepiscopal.
Notable Monuments: The National Shrine of St. Thomas Basilica in Mylapore; the National Shrine of Our Lady of Velankinni, often known as the Lourdes of the East; St. Mary's Forane Church in Kuravilangad; Kottakkavu Mar Thoma Syro-Malabar Pilgrim Church in North Paravur; St. Antony's Syro-Malabar Catholic Forane Church in Thrissur, often known as the Little Rome of India. Throughout Kerala and the Malabar Coast there are small monuments known as St. Thomas Crosses -- ancient Christian stone crosses, some of them over a millenium and a half old, that have often had churches built in association with them. Some of these are sites held by other churches, like the Assyrian Church of the East or the Anglican Church in India, but most are Syro-Malabar Catholic.
Notable Saints: St. Kuriakose Elias Chavara (January 3); St. Thomas the Apostle (July 3); St. Alphonsa Muttathupadath (July 28) ; St. Euphrasia Eluvathingal (August 29). There are a significant number of beatified, like Bl. Thevarparampil Kunjachan, who may be lifted to the general calendar at some point, particularly given that the church is quite active in investigating their causes. In addition, as a Chaldean church, the Syro-Malabar celebrate and dedicate their churches to some saints not on the general calendar who are associated with the history of the Church of the East, such as Ss. Addai and Mari and St. Hormizd, although in general only if they are already recognized in the Roman Martyrology as well.
Notable Religious Institutes: The Syro-Malabar Catholic Church has a very large number of religious orders and societies; communal works of mercy are a massive part of the devotional life of the church. Some that are especially notable with respect to Syro-Malabar history are: Carmelites of Mary Immaculate; Congregation of the Mother of Carmel; Sisters of the Destitute; Congregation of Saint Thérèse of Lisieux; Missionary Society of St. Thomas the Apostle.
Extent of Official Jurisdiction: The Major Archeparchy of Ernakulam-Angamaly; four Archeparchies and twenty-four eparchies in India; an eparchy in the United States; and an eparchy in Australia. (Sphere of influence always extends beyond the official jurisdiction due to members of the church living outside of any official jurisdiction of the church.)
Online Sources and Resources:
(These are always only a sample, but it is perhaps worth noting that the Syro-Malabar Church has perhaps the most extensive internet presence of all of the Eastern Catholic Churches.)