After death of Tamerlaine flamed up the private war between off springs of the great warrior. The war lasted approximately 5 years was won by the son of Tamerlaine - Shahruh who made his residence the city of Gerat, while the area of Maveranahr with its centre in Samarkand he gifted to his elder son Ulugbek.

  40 years, from 1409 till his tragic death, the country was ruled by Ulugbek, at that time Samarkand became one of the world's centres of medieval science. In the first part of 15th century around Ulugbek arose the scientific school, which united all outstanding astronomers and mathematics - Al-Kashi Djemshida ibn Masuda, Kazy-Zade Rumi, Ali Kushchi, Muhhamad Havofi and others.

  Ulugbek himself was not only highly educated statesman but also he was one of the most prominent astronomers and mathematicians of the 15th century. He made Samarkand one of the world's centres of science and leading city of the Islam civilization. In ancient writings it is said that Ulugbek was fair, mighty and generous person who reached the high level of learning and deeply penetrated to the essence of the things.

  In 1424 Ulugbek built a madrassa, a research institute of astronomy, and in 1429, he built magnificent three-level observatory in Samarkand. The circular observatory was over 46 metres in diameter and at least 30 metres high. It was one most unique buildings of the time. Inside was installed gigantic marble sextant.

  In 1437 Ulugbek published his most famous work, a new catalogue of stars "Zidji-Guragan" also known as "Star tracking tables of Ulugbek", the tables consists the coordinates of 1018 stars. This work was done together with the most famous scientists of Uzbekistan of the 15th century. They also calculated the length of star year, which was equal to 365 days 6 hours 10 minutes and 8 seconds while in present time it is known that star year is equal to 365 days, 6 hours, 9 minutes and 9.6 seconds. The prominent astronomer studied the yearly movements of the five bright planets: Saturn, Jupiter, Mars, Venus, and Mercury. His data is still considered to be very accurate.

  Against the stern lows of Islam Ulugbek cultivated free and easy life conditions. Sounded music, songs, were arranged magnificent feasts and holidays, he also allowed women to participate in feasts and holidays. By that time in Samarkand lived a lot of musicians and dancers who were known far beyond Samarkand.

  Ulugbek tragically died in 1449. There is a version that he was killed by his son in order to take a power in his hands.