Expansion to Sri Lanka and Burma

Sri Lanka was proselytized by Ashoka's son Mahinda and six companions during the 2nd century BCE. They converted the king Devanampiya Tissa and many of the nobility. This is when the Mahavihara monastery, a center of Sinhalese orthodoxy, was built. The Pali Canon was written down in Sri Lanka during the reign of king Vattagamani (29–17 BCE), and the Theravada tradition flourished there. Later some great commentators worked there, such as Buddhaghosa (4th–5th century) and Dhammapala (5th–6th century), and they systemised the traditional commentaries that had been handed down. Although Mahayana Buddhism gained some influence in Sri Lanka at that time, Theravada ultimately prevailed, and Sri Lanka turned out to be the last stronghold of Theravada Buddhism, from where it would expand again to South-East Asia from the 11th century.
In the areas east of the Indian subcontinent (modern Burma and Thailand), Indian culture strongly influenced the Mons. The Mons are said to have been converted to Buddhism from the 3rd century BCE under the proselytizing of the Indian Emperor Ashoka the Great, before the fission between Mahayana and Hinayana Buddhism. Early Mon Buddhist temples, such as Peikthano in central Burma, have been dated between the 1st and the 5th century CE.

The Buddhist art of the Mons was especially influenced by the Indian art of the Gupta and post-Gupta periods, and their mannerist style spread widely in South-East Asia following the expansion of the Mon kingdom between the 5th and 8th centuries. The Theravada faith expanded in the northern parts of Southeast Asia under Mon influence, until it was progressively displaced by Mahayana Buddhism from around the 6th century CE.
According to the Ashokavadana (2nd century CE), Ashoka sent a missionary to the north, through the Himalayas, to Khotan in the Tarim Basin, then the land of the Tocharians, speakers of an Indo-European language.