Ashoka was one of the most important rulers of ancient India. As king of the Mauryan dynasty, he ruled vast areas of the Indian subcontinent from 272 to 236 BCE. His territory was not only one of the first empires, but also one of the most extensive. Ashoka is seen as an innovator; in order to modernize public administration, for instance, he introduced a writing system. He also ordered the construction of hospitals and stupas. Considered a great patron of Buddhism, Ashoka is famous for the edicts he had carved on boulders and monumental pillars to promote his principles. According to Buddhist accounts, he himself became a Buddhist, and sent his son Mahinda to Sri Lanka as a missionary to spread Buddhism there.