Christianity spread into the country as early as AD 40. Tiridates III of Armenia (238–314) made Christianity the state religion in 301, partly, in defiance of the Sasanian Empire, it seems, becoming the first officially Christian state, ten years before the Roman Empire granted Christianity an official toleration under Galerius, and 36 years before Constantine the Great was baptised. Prior to this, during the latter part of the Parthian period, Armenia was a predominantly Zoroastrian country.