Qulay'a (Arabic: قليعة, romanized: Qulayʾa), also transliterated Qulay'at or Qleiat) is a village and medieval citadel in northwestern Syria, administratively part of the Tartus Governorate. According to the Syria Central Bureau of Statistics, Qulay'a had a population of 1,360 in the 2004 census.^[1] The fortress of Qulay'a was one of the several held by the Nizari Ismaili state in the Syrian coastal mountains and is locally known as Al-Sheikh Deeb Castle (Arabic: قلعة الشيخ ديب, romanized: Qal'at Sheikh Dib). The fortress stands at an elevation of 730 meters (2,400 ft) above sea level.^[2]

The Nizari Isma'ilis took control of Qulay'a around the time they came into control of Masyaf in 1140–1141.^[3] Between 1270 and 1273, Qulay'a was among several of the Nizari Isma'ili castles to have surrendered to the Mamluk sultan Baybars and annexed into the Mamluk realm.^[4]

During the Ottoman period, Qulay'a was the center of a minor nahiye (subdistrict) in the hill country west of Hama.^[2] It was mentioned in Ottoman tax records from 1547 and 1645.^[5] Unlike many other former Crusader or Nizari Isma'ili fortresses during that period, where the inhabitants of the fortress were Sunni Muslims or Isma'ili Shia Muslims amid a largely Alawite-populated countryside, by the 17th century the inhabitants of the Qulay'a castle itself were Alawites.^[6]

• Daftary, Farhad (1990). The Isma'ilis: Their History and Doctrines. Cambridge University Press. ISBN 0-521-37019-1.
• Willey, Peter (2005). Eagle's Nest: Ismaili Castles in Iran and Syria. London and New York: I. B. Tauris. ISBN 1-85043-464-6.
• Winter, Stefan (2016). A History of the 'Alawis: From Medieval Aleppo to the Turkish Republic. Princeton and Oxford: Princeton University Press. ISBN 9780691167787.