[HBPujWBe]

The split point to 2 Nikaya was happen about 100 years after Buddha death.

The Second Council convenes in Vesali to discuss controversial points of Vinaya. The first schism of the Sangha occurs, in which the Mahasanghika school parts ways with the traditionalist Sthaviravadins. At issue is the Mahasanghika's reluctance to accept the Suttas and the Vinaya as the final authority on the Buddha's teachings. This schism marks the first beginnings of what would later evolve into Mahayana Buddhism.

The Second Council

For my understanding :-

Theravadin : Try to keep original teaching of Buddha. If somebody need to write something more, can not write in Tipitaka, should write in Atthakatha. Then, if we read mahayana Tipitaka, we will find Theravadin Tipitaka about 1/3 and the other 2/3 was different.

Mahayana : The great vihicle, because many of mahayana address to Bodhisattva, Need to be a Buddha. (Exclude Zen) The famous mahayana in Thailand is Guan Yin who pretend to help everyone to Nippana and she will be the last one.

Theravada call Mahayana, Acariyavada (may wrong spell) mean teacher's teaching.(Theravada mean Thera's teaching - Thera mean the elder monks at the 2nd council convenes)