The Buddha's life and teachings were primarily associated with the kingdoms of Kosala and Magadha. He attained enlightenment under a Bodhi tree in Bodh Gaya, which was part of Magadha. His early life and significant sermons, including the First Sermon at Sarnath, took place in or near these regions. While Avanti and Gandhara were prominent kingdoms of the period, they were geographically distant from the core areas where the Buddha spent most of his life and disseminated his teachings.