How did Buddhism grow and change after the Buddha died?

Answer:

After the death of the Buddha, his teachings were preserved and developed by his disciples¹²³⁴. About three months after the Buddha's parinirvana, 500 of his senior monks met to discuss how their teacher's wisdom and the rules he developed to guide the monastic community (the Vinaya) would be preserved. This became known as the first Buddhist council².

Some 70 years after his death, a second council was held to come to terms around a set of ten disputed rules for monks and nuns. It is widely believed that this was the first schism in the Buddhist monastic community, or sangha, and two branches were formed then—one that wanted to uphold all the rules of the Vinaya, and another that wanted to relax some of them².

A third council is said to have taken place—its existence is in scholarly dispute—during the reign of the Indian king Ashoka, who converted to Buddhism around 250 BCE and was a powerful supporter and influence on the spread of the religion across the subcontinent². The council was intended to rid the sangha of corruption and heretical monks. Crucial components of the Buddhist scriptures are said to have been formalized at this meeting².

The third council was also believed to have been the genesis of teaching missions sponsored by Ashoka, where learned monks and nuns who could recite the Buddha’s teachings by heart were encouraged to act as emissaries to other lands and offer the Buddha’s dharma². These emissaries took Buddhism to Sri Lanka, Burma, and elsewhere. In the successive centuries, Buddhism spread further into East and Southeast Asia and the Himalayas and became a prominent world religion².

Buddhism expanded in the Indian subcontinent in the centuries after the death of the Buddha, particularly after receiving the endorsement and royal support of the Maurya Empire under Ashoka in the 3rd century BCE. It spread even beyond the Indian subcontinent to Central Asia and China⁵.

So, after Buddha's death, Buddhism grew significantly due to preservation efforts by his disciples, royal support from influential figures like Ashoka, and missionary work that spread Buddhism beyond India. Over time, it evolved into different branches with varying practices but maintained its core teachings.