The Buddhist Councils

Buddhist councils held in different centuries have changed the course of Buddhism and impacted its different traditions, such as early Theravada and Mahayana Buddhism.
Buddhist Councils are some of the important events that changed the course of Buddhism. After Lord Buddha attained Parinirvana in Kushinagar, India, many senior monks such as Mahakassyapa and Upali were concerned about the teachings, preachings of Dharma, and discipline of all Buddhist monks. The first Historical Buddhist Council is believed to be held in the 5th Century BCE (the date may vary) and was led by Ven. Mahakassyapa. Read more at:
https://www.originalbuddhas.com/blog/the-buddhist-council