Salweyn, also known as Salwine or Salwayn, is a proto-Somali archaeological site located in the Sanaag region of northwestern Somalia (Somaliland), near the coastal town of Heis and approximately 200 km west of Bosaso. The site dates back at least 2,000 years, or possibly earlier, and is recognized as one of the four oldest urban settlements in northern Somalia, alongside sites at Ras Hafun and Damo. It was the center of an ancient civilization and, during Classical antiquity and Late antiquity, functioned as a prominent trading center and seaport. Archaeological investigations, including those carried out in the late 19th century by the French explorer Georges Révoil, uncovered numerous Greco-Roman artifacts within its vast necropolis, which contains burials with imported commodities. Older literature identifies Salweyn with Mosylon.