The ancient Indian emperor who embraced Buddhism after the Kalinga War was Ashoka. He ruled much of the Indian subcontinent as the third Mauryan emperor during the 3rd century BCE.
The Kalinga War, fought around 261 BCE, brought the independent region of Kalinga under Mauryan control. Ashoka’s own Rock Edict XIII describes his remorse at the suffering, deaths, and deportations caused by the conquest. Afterward, he increasingly supported Buddhist teachings and promoted dhamma, a moral policy emphasizing compassion, restraint, tolerance, and nonviolence.
Ashoka did not instantly abandon government or become a monk. His conversion appears to have developed gradually, and inscriptions show him supporting the Buddhist sangha while also advocating respect for other religious communities. He commissioned pillars and rock edicts across his empire, making him one of ancient India’s best-documented rulers.
A common mix-up is treating the Kalinga War as the moment Buddhism was first introduced to him with complete certainty. Some traditions say he had already become a Buddhist before the war, but Ashoka remains the canonical quiz answer.