Siwan may refer toSivan, a month of the Hebrew calendar Siwan, a month of the Mandaean calendar The Welsh form of Joan Siwan or Joan, Lady of Wales, the wife and consort of Llywelyn the Great, Prince of Wales Siwan (play), by Saunders Lewis Sewant, beads used as a currency by Native Americans Siwan (album), a musical orchestra project by Jon Balke, and featuring Amina Alaoui Siwan, Henan, a town in Xichuan County, Henan, China