Final answer:
Emperor Ashoka, the ruler of the Maurya Dynasty, played a pivotal role in spreading Buddhism after his conversion due to the remorse he felt after the Kalinga war. He supported Buddhism through missionary work, public reforms, and by inscribing edicts that spread the religion's teachings.
Step-by-step explanation:
The Indian ruler who promoted the spread of Buddhism after his own conversion was Ashoka. Ashoka, also known as Ashoka the Great, was an emperor of the Maurya Dynasty who came to power around 268 BCE. After witnessing the massive bloodshed in the Kalinga War, he experienced a profound transformation and embraced Buddhism. Ashoka went on to establish a vast empire and initiated many reforms based on Buddhist teachings. He supported missionary efforts that helped spread Buddhism beyond India, including to Sri Lanka and Burma, and implemented a variety of public works such as hospitals, wells, and rest-houses to improve the lives of his subjects in accordance with his new beliefs. Furthermore, he had edicts inscribed on pillars and stones throughout his empire, advocating for moral living and non-violence, which were fundamental principles of Buddhism. The impact of Emperor Ashoka's patronage was instrumental in making Buddhism a world religion