It was during the Sui and Tang dynasties that China expanded into eastern Central Asia. Chinese foreign policy to the north and west now had to deal with Turkic nomads, who were becoming the most dominant ethnic group in Central Asia. To handle and avoid any threats posed by the Turks, the Sui government repaired fortifications and received their trade and tribute missions. They sent royal princesses off to marry Turkic clan leaders, a total of four of them in 597, 599, 614, and 617. The Sui stirred trouble and conflict amongst ethnic groups against the Turks.