Whatever might be the truth behind the Theravādin account, it was around the time of Aśoka that further divisions began to occur within the Buddhist movement and a number of additional schools emerged, including the Sarvāstivāda and the Saṃmitīya. All of these early schools of Nikāya Buddhism eventually came to be known collectively as "the eighteen schools" in later sources. With the exception of the Theravāda, none of these early schools survived beyond the late medieval period by which time several were already long extinct, although a considerable amount of the canonical literature of some of these schools has survived, mainly in Chinese translation. Moreover, the origins of specifically Mahāyāna doctrines may be discerned in the teachings of some of these early schools, in particular in the Mahāsānghika and the Sarvāstivāda.