This book is the first scientific biography of the ruler of Samarkand and the outstanding scientist Ulugbek - one of the most educated people of the 15th century. It is shown how under Ulugbek Samarkand became the largest center of the East, how Ulugbek created the famous Samarkand mathematical and astronomical school. The works of Ulugbek himself and the scientists of his school who created the famous “Zij of Ulugbek” are analyzed, the construction of the Samarkand Observatory, the creation of the world's largest astronomical instrument, which made it possible to achieve the highest accuracy of observations of the pre-telescopic development of astronomy, is described. For a wide range of readers interested in the development of world science.< /p>