the saint thomas christians of india, where they are known as syrian christians, though ethnically unrelated to the peoples known as assyrian, aramean or syrian/syriac, had strong cultural and religious links with mesopotamia as a result of trade links and missionary activity by the church of the east at the height of its influence. following the 1653 coonan cross oath, many saint thomas christians passed to the syriac orthodox church and later split into several distinct churches. the majority, remaining faithful to the east syriac rite, form the syro-malabar catholic church, from which a small group, known as the chaldean syrian church, seceded and in the early 20th century linked with what is now called the assyrian church of the east.