*ca.300 Bp. [[w:David of Basra|David of Basra]] undertook missionary work in India, among the earliest documented Christian missionaries in India.
*300 By this date, the Chrisitan population is about 6,200,000, or 10.5% of the population of the Roman Empire (based on population of 60 million).
*301 [[Gregory the Illuminator]] converts King Tiridates I of Armenia to the Christian faith.
*302 20,000 Martyrs burned at Nicomedia.
*303 Outbreak of the [[w:Diocletianic Persecution|Great Persecution]] (303-311), as Diocletian and Galerius launch the last and most severe persecution of Christians in the Roman Empire; martyrdom of [[George the Trophy-bearer]].