Alpqapa, Pugu Huai'en's father, led his tribe to the Tang court in the early Kaiyuan period, but after a short while came back to the Turkic court, and took sides with both the Turkic court and the Uighur tribes. At the same time, Ädiz kept marriage relationships with both the Turkic court and Sharï. Since Pugu kept a close relationship with the Uighurs, they became isolated from the tribes that surrendered. The trust between the Tang court and Pugu Huai'en was based on his special relationship with the Uighur Empire, so when the Uighurs became hostile toward the Tang, Pugu Huai'en became isolated and dangerous. Considerable evidence shows that Pugu Huai'en assaulted Chengtianjun after his rebellion, which means he wanted to get touch with Hebei warlords, that is leaders who had surrendered after the An Lushan Rebellion. This threatened the Hedong warlords, who then built an alliance with foreign tribes against Pugu Huai'en and forced him to leave Hedong.