The Syro Malabar Church was founded by St.Thomas, one of the 12 Apostles, who traveled after the Pentecostal experience, to the farthest country then known to proclaim the Good News.
He set sail to India and landed in Kodungalloor (Cranganore), Kerala in 52 A.D. He preached in different kingdoms all around the Subcontinent and established seven and a half Ecclesial Communities in Malabar, today called Kerala.
After 20 years of His mission work, He was martyred at Little Mount near Mylapore, by a fanatic Hindu priest on July 3rd in AD 72. The whole world celebrates the Martyrdom of St.Thomas on July 3rd and it is a day of obligation for the Syro Malabarians.
The Syro-Malabar Catholic Church is an East Syrian Rite, Major Archiepiscopal Church in full communion with the Catholic Church. It is one of the 22 sui iuris Eastern Catholic Churches in the Catholic Church. It is the largest of the Saint Thomas Christian denominations with around 3.8 million believers. It is also the second largest Eastern Catholic Church in communion with the Bishop of Rome.
The church is headed by the Major Archbishop Mar George Cardinal Alencherry. (He is one among the 22 new cardinals elevated by Pope Benedict XVI )
Saint Alphonsa is the first saint from within the Church. The members of the Church are locally known as Nasranis.
Hope this helps!