the reigns of Dutugamy and Valagamba (c. mid-2nd century BCE to mid-1st century BCE). K. M. de Silva states that by the first century BCE, Buddhism was "well established in the main areas of settlement." De Silva also notes that as Buddhism was adopted by the Sinhalese, it assimilated pre-Buddhist cults, rituals and ceremonies. Buddhism became a powerful factor in the unification of Sri Lankan under a single political power with a unified culture. The Mahavamsa §29 records that during the rule of the Greco-Bactrian King Menander I (165/155 –130 BCE), a Yona (Greek) head monk named Mahadharmaraksita led 30,000 Buddhist monks from "the Yona city of Alasandra" (Alexandria in the Caucasus, around north of modern Kabul, Afghanistan) to Sri Lanka for the dedication of the Ruwanwelisaya Stupa in Anuradhapura. This happened during the reign of the Sinhala king Dutugamunu (161 BC to 137 BCE), who was the first to truly unite the various Sri Lankan states on the island into one polity by defeating the Tamils who had conquered the north. Theravāda in the Anuradhapura Kingdom The culture, laws, and government of the Anuradhapura Kingdom (as well as the other kingdoms which were mostly subservient to it) was strongly influenced by Buddhism. Over much of the early history of Anuradhapura Buddhism, there were three subdivisions of Theravāda, consisting of the Mahāvihāra, Abhayagiri and Jetavana sects. All three were based in Anuradhapura, the large and populous capital of the ancient Sinhalese kings, which saw themselves as the defenders and supporters of Buddhism. The Mahāvihāra was the first tradition to be established, while Abhayagiri Vihāra and Jetavana Vihāra were established by monks who had broken away from Mahāvihāra and were more open to Mahayana. According to A. K. Warder, the Indian Mahīśāsaka sect also established itself in Sri Lanka alongside the Theravāda, into which they were later absorbed. Northern regions of Sri Lanka also seem to have been ceded to sects from India at certain times. Abhayagiri Theravādins maintained close relations with Indian Buddhists over the centuries, adopting many of the latter's teachings, including many Mahāyāna elements, whereas Jetavana Theravādins adopted Mahāyāna to a lesser extent. The Mahāvihāra tradition meanwhile considered many of the Mahāyāna doctrines, such as Lokottaravāda ("transcendentalism"), as heretical and considered the Mahāyāna sutras as being counterfeit scriptures. Religious debate and conflict among these sects were also not unusual, particularly because the close relationship between the sangha and