The River Roul or Ruldin, is a great river in southeastern Anásthias, flowing southeast from the mountains through Taur-Dji-Oum to its mouth in Tiernas Bay. The river is the formal boundary between Munatan and Otekahré.
At its mouth the river is the widest in the Civilised World and regularly floods, creating an inhospitable landscape of swamps and mudflats.