Seistan

Seistan, or Hamoon, LAKE, a large, irregularly-shaped, shallow lake or swamp in the west of Afghanistan, close to the frontier of the Persian province of Khorassan, a division of which province (mainly steppe) is named Seistan after it. The lake is not a single expanse of water, but is divided into three depressions. Great part of the area is generally dry; but, as the basin has no outlet, when the Helmund (q.v.) and its other feeders are in flood this lake regularly overflows its boundaries, fertilising large tracts of country.