Although Christianity arrived in Wales sometime in the Roman occupation, it was initially suppressed. The first Christian martyrs in Wales, Julius and Aaron, were killed around AD 304. The earliest Christian object found in Wales is a vessel with a Chi-Rho symbol found at Caerwent. Christianity became the official religion of the Roman Empire in the 4th century. After the Roman legions withdrew in the 5th century Anglo-Saxon invaders gradually conquered eastern and southern Britain but were unable to make inroads into Wales, cutting off Wales from the Celts in Scotland, Cornwall and Cumbria. The writer Gildas drew sharp contrasts between the Christian Welsh at this time and the pagan Anglo-Saxon invaders.