The Ḥudūd al-ʿĀlam (Arabic: حدود العالم, lit. "Boundaries of the World," "Limits of the World," or also in English "The Regions of the World") is a 10th-century geography book written in Persian by an anonymous author from Guzgan (present day northern Afghanistan), possibly Šaʿyā bin Farīghūn. The title in full is حدود العالم من المشرق الی المغرب (Ḥudūd al-ʿĀlam min al-Mashriq ilá l-Maghrib, lit. "The Boundaries of the World from the East to the West").
The sections of its geographical treatise which describes the margins of Islamic world, are of great historical importance, including early descriptions of the Turkic peoples in Central Asia. Also noteworthy is the archaic language and style of the Ḥudud, which makes it a valuable Persian linguistic document as well.