The doctrines of the early Mahayana are difficult to define because doctrinal widening is a feature of its development. Interpretations and practices, which were thought to be skilful means (upaya) to aid understanding of the way things are, were added to the closed canons of the non-Mahayana schools initially by small minorities of geographically widespread monks. One of the earliest doctrinal developments was to regard the Buddha as more than just a human being and instead as transcending the human realm and still available in the world. The aspiration of monks began to be towards full Buddhahood not arhatship, emphasising altruistic ideals more than individual release from samsaric existence. The spiritual ideal began to be embodied by the Bodhisattva, an aspirant Buddha who vowed to postpone final enlightenment until all beings were enlightened. This goal was also available to the laity.

The movement that later called itself Mahayana, `Great Vehicle' arose during the period from 100 BCE to 100 CE. Early Mahayanists did not entirely reject non-Mahayana doctrine and lived alongside non-Mahayana monks in such a way that their public behaviour did not differ, since all monks lived according to the vinaya rule. The rise of Mahayana ideas is thought by some to have originated among elements within the laity who were disgruntled with the attitude of monastics. However it seems more likely that the new ideas were developed within the monasteries by the religious specialists.
     The developing Mahayana sutras were considered, by those who adopted them, to be the spoken word of the Buddha and usually began with the traditional formula, "thus have I heard". Whereas the non- Mahayana sutras were passed through oral tradition within a canon which had been closed at the time of the first council, approximately seventy years after the Buddha's death,  Mahayana sutras continued to be `discovered' or revealed. It was often claimed that these sutras had been preached by the Buddha to Bodhisattvas in other realms or to his most advanced disciples and were therefore not available until the time was right. The sutras were communicated by heavenly Bodhisattvas to monks in advanced meditational states and the texts themselves became the focal points for devotional practices. It is likely that monks and nuns in geographically dispersed monasteries, with little contact between them, revered different sutras. Although such activities probably began as early as the first century BCE, the Mahayana did not have a clear self-awareness until at least the fourth century CE. Literature developed after this time shows clear indications of diverse but characteristically Mahayana doctrines while some of the earliest proto-Mahayana texts, for example the early Perfection of Wisdom literature, lack key  Mahayana concepts. By the sixth century CE the Mahayana had its own identity and from this time the texts show evidence of disparaging attitudes towards schools of doctrine called by the  Mahayanists the Hinayana, `the inferior way'.  

At about the same time as the emergence of the Mahayana images of the Buddha were beginning to be depicted. The Buddha was sometimes accompanied by pairs of bodhisattvas whose elegant garments and adornments contrasted with the Buddha's simple clothing.

It is impossible to determine with any accuracy the number of Mahayanists in ancient India. During his visit to India in the seventh century Hsüan-Tsang counted 200,000 monks, perhaps half of whom were Mahayanists.

Since monks influenced by  Mahayana ideas were widespread there was no early headquarters or main centre.