Olug Moxammat (Ulugh Muhammed, Makhmet, Ulu-Makhmet, Tatar: Oluğ Möxämmät) (d. 1445) was khan of the Golden Horde (1419 - 1422/23), the founder and the first khan of Kazan Khanate (1437 - 1445). Olug Moxammat was a descendant of Jochi, and consequently a Genghizid. By some accounts, he was a son of Jalal ad-Din khan, and grandson of Tokhtamysh, by other accounts he was a son of Khasan, one of Edigu's puppet khans.
Olug Moxammat together with Dawlat Berdi was one of the two major powers in the desintegrating Golden Horde. He acted as a khan of the Horde from 1419 until he and Dawlat Berdi were defeated by Baraq khan in 1422 or 1423. In 1424 he appeared at the court of Vytautas the Great in Grand Duchy of Lithuania, while Dawlat Berdi went to Crimea. Before 1428, with help of Vytautas, Olug Moxammad assembled an army an took Saray from Baraq, establishing himself again as a major power on the territories of the Golden Horde. A letter dated March 14, 1428, from Olug Moxammat to Murad II, sultan of Ottoman Empire is known. In this letter Olug Moxammat writes that the relatons with sultan were interrupted by Baraq, who temporarily gained power in Golden Horde (Desht-i Qipchaq, as the steppe was called). Now, he is victorious and his army defeated and routed Baraq and Mansur.
After regaining the throne of the Horde, Olug Moxammat unsuccessfully invaded Crimea against his old rival Dawlat Berdi. He was likely supported by Qarachi. In 1430 Olug Moxammad lost his major supporter as Vytautas died. That put an end to Moxammat's plans to conquer Crimea. The priorities shifted to Lithuania, where he supported Sigismund I Kestutian against Svitrigaila in the fight for Lithuanian throne. Displaced Svitrigaila in turn supported Moxammat's rival Sayyid Ahmad I, who in 1433 gained the Golden Horde throne. Vasili II of Russia also supported Sayyid Ahmad in order to weaken Olug Moxammat.
Sigismund was a weaker leader than Vytautas and could not offer as much support. Sayyid Ahmad quickly consolidated power. In 1433 he participated in a civil war in Crimea and took Solkhat, capital of Crimean ulus which resulted in Devlet Haci Ghiray becoming a ruler there. Moxammat was forced to leave Horde and move to upstream Volga, where in 1437 he captured town Belev (now in Tula Oblast) and attempted to establish a dominion there. He could not maintan control. Vasili II recaptured the town next year.
In 1437—1438 Moxammat besieged and then captured Kazan, where he established Kazan Khanate. An alternative theory suggests that Moxammat usurped the throne of principality which asserted a degree of independence from Golden Horde earlier.
In 1439 he made a raid on Moscow, sieged it for ten days, burned villages around it, but failed to capture the city. A few years later he captured Nizhny Novgorod. In the Spring of 1445 he sent an army under command of his sons Yusuf and Mahmudek to Muscovy. The campaign was exceptionally successful. The most significant battle was fought on June 7, 1445 near Yefimyev monastery (Battle of Suzdal). Kazan army managed not only to defeat Russian army, but also to capture Vasili II. Grand Duke was released after paying a ransom on October 1 that year.
Upon his death, the throne pased to his son Mahmudek. The other two sons Qasim and Yusuf fled. There are at least three versions of Moxammat's death. According to the first, he died from old age or disease. According to the second, offered by Kazan Chronicle, he was killed by Mahmudek. This Chronicle also claims that brothers were killed as well, which undermines the validity of this claim because both brother were known to live much longer than 1445. And by the third, Moxammat was killed by his brother Kara-Yusuf, with Qasim and Yusuf siding with uncle, while Mahmudek with father.
Olug Moxammat's descendants ruled Kazan until 1518.
Olug Moxammat kept in touch with Shah Rukh (Timurid dynasty).
Olug/Uligh/Ulu was not his personal name, but a title which could be loosely translated as Great or Patriarch. The title was allegedly used to distingush him from Kuchuk Muhammad (Small or Junior Muhammad), khan of Big Horde.