Extensive development of the city of Anuradhapura took place during the reigns of the kings such as Dutugemunu, Valagamba, Vasabha, Mahasen and Dhatusena. The rapid development which Anuradhapura was thus experiencing came to an abrupt setback with the invasion of the Pandyans in the 9th c. A.D. and the Colas from South India in the 10th c A.D.
The old Anuradhapura which was situated on the west bank of a tributary of Malvatuoya was bounded by the Bulankulama reservoir on its west, Basawakkulama ( Abhaya) reservoir on its south west, Tisawewa reservoir on its south and the Nuwara ( Jaya) reservoir on its East. From the spread of the ruins found in the ancient city of Anuradhapura it could be surmised that the city was divided in to two sections.
The Inner City comprised the buildings belonging to the royalty while the Outer City consisted of ecclesiastical buildings. The observation of the spatial arrangement of the monasteries reveals that Mahavihara, Jetavana, Abhayagiri, the three great monasteries and the peripheral monasteries together with the royal gardens are located as one complex in the outer city.