Southern Mesopotamia was essentially agrarian and depended on artificial irrigation. The earliest cuneiform evidence for fully-developed irrigation networks stems from royal inscriptions and archival records from a temple archive from the city-state of Lagas, ca. 2475–2315 BC. These sources testify to a four-level irrigation network, probably established upon the unification of the state by Urnanse and Eanatum. From the river, water flowed to primary canals with regulators, and from there branched off to secondary canals. Distributors regulated the water flow to the fields. The construction of primary canals and regulators was conducted by the ruler who drew on the corvée troops of the temples. The temples maintained the lower-level irrigation structures, such as the distributors and dikes in their fields.