The Mahāsaṃghika (Majority) sect of Buddhism was formed in the first Buddhist schism around 320 BCE. It split from the Sthaviravāda (Elders) school. The Mahāsaṃghikas were primarily situated in Northwestern India but also with an important presence in SE India around Amaravati and Nagarjunakonda (the Sthaviravādins were in the Northeast).
The Mahāsaṃghikas differed from the elders in including lay practitioners and non-enlightened monks at the communal meetings which constituted the governmental body for each saṅgha, allowing monks to use gold and silver and eat twice a day, and also asserted that the historical Buddha was a manifestation of a transhistorical Buddha, and phenomena are illusory and empty.
The Mahasamghika are often regarded as one of the sources of Mahāyāna doctrines.
At the points where they differ, Reginald sees a monastic bias in the telling of the story.
This is established by comparing various early scriptures including the Pali Canon and what has survived of the Dharmagupta, Sarvastivadin, and Mahasamghaka canons.
What emerges, Ray argues, is a picture in which the original ideal was the forest renunciant, but with the rise of settled monasticism the renunciants began to be occluded in Buddhist texts which were preserved by the settled monastics.
Still, in term of Abbhidharma, Sarvastivadin (who had been rejected by the 3rd council, according to the Theravada tradition) and the Dharmaguptaka which were both dominant in Kushan Empire seems to have had major influence.
In term of vinaya practice, Mahasamghaka branch of sects which emphaised greater openeness might played dominant role.
Monks representing different theological orientation could live in the same Sangha as long as they practice the same vinaya.