Kala Wewa built by the King Datusena in 460 A.D, is a reservoir complex consisting of two reservoirs, Kala Wewa and Balalu Wewa. It has the capacity to store 123 million cubic meters of water. This reservoir complex has facilitated with a stone made spillway and three main sluices. From the central major sluice, a 40 feet wide central conveys water to feed thousands of acres of paddy lands and ends at the historical capital Anuradhapura city tank Tissa Wewa meandering over 87 km (54 mi) at a slope of 6 inches per mile and is another wonder of primeval hydraulic engineering facility in ancient Ceylon.

Dhatusena was a king of Sri Lanka who reigned from 455 to 473 AD. He was the first king of the Moriyan dynasty. In some records, he is also identified as Dasenkeli. Dhatusena reunited the country under his rule after twenty six years of anarchy, defeating the six Dravidians that were ruling the country at that time. Dhatusena built large reservoirs and canals to augment the agriculture in the country.