Ulugh Bek (Uzbek: Muhammad Tarag'ay Ulug'bek, ???????? ??????? ???????; Persian: ????? ???? ???? ?? ????? ??????? - M?rz? Muhammad T?raghay bin Sh?hrukh Ulu? Bek) (22 March 1394 in Sultaniyeh (Persia)  27 October, 1449 (Samarkand) was a Timurid ruler as well as an astronomer, mathematician and sultan. His commonly-known name is not truly a personal name, but can be loosely translated as 'Great Ruler' and was the Turkic equivalent of Timur's Perso-Arabic title Am?r-e Kab?r. His real name was M?rz? Mohammad T?raghay bin Sh?hrokh. Ulugh Beg was notable for his work in astronomy-related mathematics, such as trigonometry and spherical geometry. He built the great observatory in Samarkand, between 1424 and 1429.