By 1360, Urus Khan had set up court in Sighnaq. He was named Urus, which means Russian in Turkish language, presumably because "Urus-Khan's mother was a Russian princess... he was prepared to press his claims on Russia on that ground." In 1372, Urus marched west and occupied Sarai. His nephew and lieutenant Tokhtamysh deserted him and went to Timur for assistance. Tokhtamysh attacked Urus, killing his son Kutlug-Buka, but lost the battle and fled to Samarkand. Soon after, another general Edigu deserted Urus and went over to Timur. Timur personally attacked Urus in 1376 but the campaign ended indecisively. Urus died the next year and was succeeded by his son, Timur-Melik, who immediately lost Sighnaq to Tokhtamysh. In 1378, Tokhtamysh conquered Sarai.