Editing Samarkand (section)

===[[Ulugbek|Ulugh Beg]]'s period (1409–1449)===
[[File:Ulugh Beg's Astronomic Observatory.jpg|thumb|left|Many prominent astronomers worked at [[Ulugh Beg Observatory|Ulugh Beg's observatory]], which contained this mural sextant, constructed in Samarkand during the 15th century.]]
Between 1417 and 1420, Timur's grandson [[Ulugh Beg]] built a [[madrasa]]h in Samarkand, which became the first building in the architectural ensemble of Registan. Ulugh Beg invited a large number of astronomers and mathematicians of the Islamic world to this madrasah. Under Ulugh Beg, Samarkand became one of the world centers of medieval science. In the first half of the 15th century, a whole scientific school arose around Ulugh Beg, uniting prominent astronomers and mathematicians including [[Jamshid al-Kashi]], [[Qāḍī Zāda al-Rūmī]], and [[Ali Qushji]]. Ulugh Beg's main interest in science was astronomy, and he constructed an observatory in 1428. Its main instrument was the [[Mural instrument|wall quadrant]], which was unique in the world.<ref>{{Cite web |url=https://mathshistory.st-andrews.ac.uk/Biographies/Ulugh_Beg/ |title=Ulugh Beg – Biography |website=Maths History}}</ref> It was known as the "Fakhri Sextant" and had a radius of 40 meters.<ref>{{Cite book |last=Ulugh Beg |title=Dictionary of Scientific Biography}}</ref> Seen in the image on the left, the arc was finely constructed with a staircase on either side to provide access for the assistants who performed the measurements.