The rules governing the life and organization of the saṅgha (in the restricted sense) are found in Vinayapiṭaka. The saṅgha is basically mendicant, and it has no hierarchical organization (apart from a senior monk, Skt., sthavira; Pāli, thera). The development of Mahāyāna did not diminish the importance of the saṅgha, even though routes to enlightenment/salvation were opened up outside the saṅgha. The vinaya traditions persisted, and only in Japan did the organization of schools diminish the importance of the monastic saṅgha. In 1966, the World Buddhist Saṅgha Council was established.
"Sȧgha." The Concise Oxford Dictionary of World Religions. . Encyclopedia.com. (February 24, 2018). http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/sagha
"Sȧgha." The Concise Oxford Dictionary of World Religions. . Retrieved February 24, 2018 from Encyclopedia.com: http://www.encyclopedia.com/religion/dictionaries-thesauruses-pictures-and-press-releases/sagha