The Old Testament of the Peshitta was translated from Hebrew around second century. The New Testament of the Peshitta had become the standard by the early 5th century, replacing two early Syriac versions of the gospels.
In earlier time different books of gospel was in circulation. Tatian the Assyrian, who preached Christianity in Mesopotamia using song verses, produced a unified version in one book of the four Gospels. This unified version got famous by the name, Diatesseron meaning “harmony of the four”. Diatessaron was used as the standard Gospel text in Syriac Christian community. It was alluded by many Syrian writers like St. Ephrem the Syrian.
The Acts of the Apostle Saint Thomas and Acts of the Apostle Saint Adai were the other circulated versions of Gospel in early history.
The name of Rabbula, Bishop of Edessa (d. 435) is connected with the production and replacement of Diatessaron and Acts with Peshitta.
All the St. Thomas Christian churches, uses the Peshitta version in Malayalam.