西突厥
Historians have generally viewed Emperor Gaozong as a weak ruler, inattentive to the business of the state. Because he was always controlled by his wife, he was criticized for leaving such rule business to Empress Wu. During the first part of his reign, Tang territorial gains, which started with his father Emperor Taizong, continued, including the conquest of Baekje, Goguryeo, and the Western Turkic Khaganate, but throughout the 670s, much of those gains were lost to the Tibetan Empire, Silla, Khitan, and Balhae. Further, territory previously conquered that belonged to both the Göktürks and the Western Turkic Khaganate were subjected to repeated rebellions.