The Chaldean Rite, or East Syrian Rite is a rite that is practiced by the Church of the East and its modern descendants, the Assyrian Church of the East, the Ancient Church of the East, the Chaldean Catholic Church, and the Syro-Malabar Catholic Church. The Chaldean Catholic Church and the Syro-Malabar Catholic Church are in full communion with the Holy See. Thomas the Apostle established Christianity in Mesopotamia, Assyria, and Persia, when he travelled to India. The First Council of Ephesus in 431, said that the ideas and teachings of Nestorius were false. These teachings are commonly known as Nestorianism. The Church of Seleucia-Ctesiphon did not share this opinion, and split from the other churches. The church was very successful, and quickly spread. The conquest of Tamerlane in the 15th century, almost destroyed the church, and reduced itto a few communities. Differences in opinion resulted in the current situation. Two of the four churches are in full communion with the Holy See. All the churches commonly use the Syrian language for their texts.