The 'Alms Hall' of the Mahavihara sect, Anuradhapura, Sri Lanka.

Guard-stone at the entrance to the 'Alms Hall'.

A 'seven-headed cobra' as depicted in the above 'guard-stone'. The 'Nagas' extended their patronage to Buddhism from its early years. The iconic representation of this race in Sri Lanka surpasses religious divides.

A stone 'rice bowl' which was filled with boiled rice and was used to feed around 3000 Buddhist monks in the 2nd Century BC.

'Over much of the early history of Buddhism in Sri Lanka, three subdivisions of Theravāda existed in Sri Lanka, consisting of the monks of the Mahāvihāra, Abhayagiri Vihāra, and the Jetavana Vihāra.^[2]Mahāvihāra is the first tradition to be established, while Abhayagiri Vihāra and Jetavana Vihāra is established by monks who separated from Mahāvihāra tradition.^[2] According to A.K. Warder, the Indian Mahīśāsaka sect also established itself in Sri Lanka alongside the Theravāda, into which they were later absorbed.^[2] Northern regions of Sri Lanka also seem to have been ceded to sects from India at certain times.^[2]

According to the Mahavamsa, the Mahavihara was destroyed during sectarian conflicts with the Theravada monks of the Abhayagiri Vihara during the 4th century.^[3] These Mahayana monks incited King Mahasena to destruct the Mahavihara. As a result of this, a later king expelled the Mahayana monks from Sri Lanka^{[citation needed]}.

The traditional Theravadin account provided by the Mahavamsa stands in contrast to the writings of the Chinese Buddhist monk Faxian (Ch. 法顯), who journeyed to India and Sri Lanka in the early 5th century (between 399 and 414 CE). He first entered Sri Lanka around 406 CE and began writing about his experiences in detail. He recorded that the Mahavihara was not only intact, but housed 3000 monks. He also provides an account of a cremation at Mahavihara that he personally attended, of a highly respected śramaṇa who attained the arhatship.^[4] Faxian also recorded the concurrent existence of the Abhayagiri Vihara, and that this monastery housed 5000 monks.^[5] In the 7th century CE, Xuanzang also describes the concurrent existence of both monasteries in Sri Lanka. Xuanzang wrote of two major divisions of Theravāda in Sri Lanka, referring to the Abhayagiri tradition as the "Mahāyāna Sthaviras," and the Mahāvihāra tradition as the "Hīnayāna Sthaviras."^[6] Xuanzang further writes:^[7]

The Mahāvihāravāsins reject the Mahāyāna and practice the Hīnayāna, while the Abhayagirivihāravāsins study both Hīnayāna and Mahāyāna teachings and propagate the Tripiṭaka.'

http://en.wikipedia.org/wiki/Mahavihara