The second largest of the stupas in Sri Lanka, Abhayagiri Stupa has been built by King Vattagamini alias Valagamba (89-77 BC). This extends up to an extent of nearly 200 hectares. According Bhikkhu Fa-hsein who visited Sri Lanka in the fifth century there had been three thousand resident bhikkhus in the Mahavihara and five thousand bhikkhus in the Abhayagiri.
The development of Abhayagiri reached its peak in the reign of King Mahasen and was the centre of Mahayana Buddhism. Buddhist buildings found in the environs of Abhayagri indicate that this complex had been an important educational institution both locally and internationally.