To Asoka, dhamma was a way for people to treat each other and animals with respect. Dhamma was related to dharma, which is the fundamental law that Hindus, Buddhists, and Jainists believe applies to all beings.
As a Buddhist emperor, Ashoka believed that Buddhism is beneficial for all human beings, as well as animals and plants, so he built a number of stupas. He also well spread Buddhism to neighboring kingdoms.