The Silent Khan in series
Faced with this opportunity, Tang Xuanzong naturally refused to pass it up. In 715, Tang Xuanzong took charge of second Northern Expedition, and Xue Na was general manager of Shuofang Road, in charge of affairs of Northern Expedition. In 716, Emperor Xuanzong of Tang issued "Order of Xue Na and Nine Families to fight and silently sip system" in first month, and Northern Expedition officially began. After that, Tang Dynasty army moved towards desert in three groups, but retreat was not smooth. Both Central Route Army and Eastern Route Army were attacked by Turks, while Western Route Army won a major victory under command of Zhang Zhiyun's leadership, achieving goal of fighting with Tie Le. meetings.
At this time, Silent Khan is busy suppressing uprising of various ministries. During conquest of Bayegu Rebellion, Mo Chuo Han returned with a great victory and showed arrogance. On path of Mochu Khan's class, Huihe tribe launched a mid-way surprise attack and Mochu Khan was killed. The hero who ruled Mobay for 24 years just fell.
Xue Na (eldest son of Xue Rengui)
After Tang Dynasty army learned that Mo Chuo Han had been killed, they all returned to court. After that, Tang Xuanzong believed that border issues had been basically settled, so he decided to cultivate culture and suppress military affairs, reuse Song Jing, Yao Chong and other civil servants, and created brilliant "Kaiyuan Prosperous Era". However, not all of post-Turkic forces died. Soon after Tang army returned to court, Turks rose again, and struggle between Tang and Turks would continue for many years.Recommended reading
Rise and fall of Turkic Khanate: (1) Why did Turks revive?
Rise and fall of post-Turkic Khanate: (2) Turkic renaissance, era of Tien Khan is gone forever
The Rise and Fall of Post-Turkic Khanate: (3) An Expedition to Western Regions with Power of Whole Country, Northern Expedition of Tang Dynasty was in vain
Rise and fall of late Turkic khanate: (4) all-round Turkic rejuvenation, loss of face of Tang dynasty