advanced westward, intent on taking over Sarai and the central and western portions of the Golden Horde. His military power intimidated his former host Qāghān Beg in the Ulus of Shiban and Qāghān Beg's cousin, the reigning khan ʿArab Shāh, who both submitted to Tokhtamysh. Now khan at Sarai, he crossed the Volga to eliminate the powerful beglerbeg Mamai, master of the westernmost portions of the Golden Horde. Weakened by his defeat at the hands of the Russians at the Battle of Kulikovo earlier that year, and by the death of his puppet khan Tūlāk, Mamai was defeated by Tokhtamysh on the Kalka river in the autumn of 1380, after Tokhtamysh had enticed away a number of Mamai's emirs. Mamai fled to the Crimea, but was eventually eliminated by Tokhtamysh's agents, who had followed in pursuit, in late 1380 or early 1381. From a fugitive, Tokhtamysh had become a powerful monarch, the first khan in over two decades to rule both halves (wings) of the Golden Horde. In the space of a little over a year, he had made himself master of the left (eastern) wing, the former Ulus of Orda (called White Horde in some Persian sources and Blue Horde in Turkic ones), and then also master of the right (western) wing, the Ulus of Batu (called Blue Horde in some Persian sources and White Horde in Turkic ones). This promised to restore the greatness of the Golden Horde after a long period of division and internecine conflict. Tokhtamysh proceeded to solidify his authority with wisdom and restraint. Already in early 1381, he restored peace with the Genoese of the Crimea, ensuring himself a steady income. He similarly sought the cooperation of the emirs and tribal chieftains by confirming the privileges that had been conferred to them in the past. Campaign against Moscow Encouraged by his success, as well as the growth of his manpower and wealth, Tokhtamysh next turned to the Russian principalities, although he did not necessarily seek a conflict from the start. Similarly, the Grand Prince of Vladimir-Suzdal, Dmitry Donskoy had recently defeated Mamai at great cost at Kulikovo, and was not looking for a confrontation, as he would have had difficulty to muster a great army again. He duly acknowledged Tokhtamysh as the new khan and his suzerain, but although he sent rich gifts, Dmitrij withheld the payment of tribute. When Tokhtamysh's envoy, Āq Khwāja,