he had allowed the Venetians to establish a colony at Tanais on the Don. New Sarai During the reign of Öz Beg, Sarai (literally meaning "palace" in Turkish and a hotel / inn / temporary residence in Persian and Urdu) was more quickly becoming a main commercial center and industrial trading center of the country rather than just a political center. The expression of Mongol camp mentality, following Ash and the nearby absence of some structures. To successfully spread Islam, it was necessary to build a mosque and other "elaborate places" like baths, an important element of Muslim culture. Sarai attracted merchants from European, Asian and Islamic countries as well as Middle East. Slave trade flourished due to strengthening ties with Mamluk Sultanate. Successful commercial revolutions require new markets and caravans: "places where merchants find their way." Growth of wealth and increasing needs of production always stimulate population growth. This did not suffice solely in Sarai. The accretion of the dwellings in the region transformed the capital into the center of a large Muslim government, giving it the appropriate aspect and status. Öz Beg actually came to build a new city, which received the official name Saray al-Jedid or New Sarai. Relationship with Russian princes Öz Beg supported the earliest princes of Muscovy—his brother-in-law Yury of Moscow (or Yuri) and Yury's successor Ivan Kalita (or Ivan Daniilovich, later, Ivan I of Moscow)—against their relatives, the westward-leaning Princes of Tver. Four of these latter rulers—Mikhail of Tver, his sons Dmitry (or Dmitri; nicknamed The Terrible Eyes) and Alexander Mikhailovich, (or Aleksandr) and his grandson Theodor (or Fyodor)—were all killed in Sarai at Öz Beg's behest. In 1317, Mikhail Yaroslavich defeated Yuri at a village called Bortenevo. Mikhail captured Yuri's wife, Konchaka, who was the Khan's sister. Unluckily, Konchaka died when she was in the custody of Mikhail; Yuri announced to the Khan that she had been poisoned by order of Mikhail. He and Yuri were summoned to the court of Golden Horde for a trial, after which Mikhail was beheaded in December 1318. Following Yury's machinations, which prompted the Khan to grant the yarlik (patent of office for the title of Grand Prince of Vladimir) to Moscow and led to their father's execution by the Horde, Dmitry and his brother, Alexander, fought a series of battles with Yury and intrigued against him at the Horde, culminating in Dmitry's acquisition of the