Christianity in Asia has its roots in the very inception of Christianity, which originated from the life and teachings of Jesus in 1st-century Roman Judea. Christianity then spread through the missionary work of his apostles, first in the Levant and taking roots in the major cities such as Jerusalem and Antioch. According to tradition, further eastward expansion occurred via the preaching of Thomas the Apostle, who established Christianity in the Parthian Empire (Iran) and India. The very First Ecumenical Council was held in the city of Nicaea in Asia Minor (325). The first nations to adopt Christianity as a state religion were Armenia in 301 and Georgia in 327. By the 4th century, Christianity became the dominant religion in all Asian provinces of the Eastern Roman Empire.