Buddhist Schools — Key Changes

Entry	Year	Description	Impact
First Doctrinal Divergence (Post-Second Council)	c. 383 BCE	The split between Sthaviravada and Mahasanghika over monastic rules and interpretations of the Arhat ideal. Mahasanghikas held more liberal views, believing Arhats could fall from grace and that the Buddha was supramundane.	Led to the formation of distinct early Buddhist schools, setting the stage for further doctrinal evolution and the eventual emergence of Mahayana. It showed that even fundamental interpretations of the Vinaya and Dharma were subject to debate.
Emergence of the Bodhisattva Ideal (Early Mahayana)	c. 1st Century BCE - 1st Century CE	A significant shift from the Arhat ideal of individual liberation to the Bodhisattva ideal of universal salvation, where an enlightened being postpones Nirvana to help all sentient beings. This was accompanied by the development of new sutras.	Revolutionized Buddhist practice and philosophy, making enlightenment accessible to a broader populace (lay practitioners) and emphasizing compassion. It formed the core of Mahayana Buddhism, distinguishing it sharply from earlier traditions.
Development of Tantric Practices (Vajrayana)	c. 7th Century CE onwards	Incorporation of esoteric rituals, mantras, mandalas, and yogic techniques (tantras) into Buddhist practice, aiming for rapid enlightenment in a single lifetime. This 'Diamond Vehicle' built upon Mahayana philosophy but introduced distinct methodologies.	Created a distinct and powerful branch of Buddhism, particularly in Tibet and the Himalayas. It offered an accelerated path to Buddhahood, often involving complex initiations and guru-disciple relationships, profoundly shaping the cultural and religious landscape of these regions.