Battle of Canhe Slope - Prior Later Yan/Northern Wei Relations

Prior Later Yan/Northern Wei Relations

Northern Wei's predecessor state Dai had previously been a vassal to Later Yan's predecessor state Former Yan, before both were destroyed by Former Qin -- Former Yan's falling in 370 and Dai falling in 376—and the last prince of Dai, Tuoba Shiyijian, had successively married two Former Yan princesses as his wives, in 344 and 362. After Former Qin suffered a major defeat against Jin forces at the Battle of Fei River in 383 in a failed bid to unite China, it began to disintegrate, and, among others, Later Yan, with Murong Chui, the uncle of Former Yan's last emperor Murong Wei, as emperor (Emperor Wucheng), took over Former Yan's old territory and people; and Northern Wei, with Tuoba Shiyijian's grandson Tuoba Gui as prince, took over Dai's former territory and people.

After the establishment of Later Yan and Northern Wei, the lord/vassal relationship resumed between Later Yan and Northern Wei. Early in his reign, Tuoba Gui had often met opposition from powerful individuals within his own state, and had to rely on Later Yan aid to quell the rebellions. For example, in 386, when Tuoba Gui faced a rebellion led by the Xiongnu chief Liu Xian (劉顯) and Tuoba Shiyijian's youngest son Tuoba Quduo (拓拔屈咄), he turned to Later Yan for help, and Later Yan forces, commanded by Murong Chui's son Murong Lin the Prince of Zhao, helped Tuoba Gui to put down the rebellion. A 387 joint operation between Northern Wei and Later Yan finally crushed Liu Xian's power.

However, Tuoba Gui was having designs against Later Yan and, when he sent his cousin Tuoba Yi (拓拔儀) the Duke of Jiuyuan to offer tributes to Murong Chui for him in 388, he asked Tuoba Yi to carefully examine the situation at the Later Yan court to observe any weaknesses. Murong Chui, displeased that Tuoba Gui did not personally come to pay tribute, interrogated Tuoba Yi, but allowed him to depart. Tuoba Yi reported to Tuoba Gui that, in his opinion, Murong Chui was old, his crown prince Murong Bao was weak, and that Murong Chui's brother Murong De the Prince of Fanyang was overly ambitious, which should cause internal problems for Later Yan upon Murong Chui's death. He opined that while Tuoba Gui should not attack Later Yan at that time, once Murong Chui died, there would be opportunity to do so. Despite his planning, however, he continued joint operations with Later Yan, and in 390 and 391, he and Murong Lin defeated the Helan (賀蘭), Getulin (紇突鄰), and Gexi (紇奚) tribes together.

However, later in 391, an incident would occur that would cause the states to break relations. Tuoba Gui sent his brother Tuoba Gu (拓拔觚) to offer tributes to Murong Chui. Murong Chui's sons and brothers had Tuoba Gu detained and ordered Tuoba Gui to offer good horses in exchange for Tuoba Gu's freedom. Tuoba Gui refused and further broke relations with Later Yan, entering into an alliance with Later Yan's rival for legitimate succession to Former Yan, Western Yan's emperor Murong Yong. Tuoba Gu, meanwhile, was kept under detention by Later Yan, albeit treated as an honored guest otherwise. In 394, when Murong Chui led a campaign against Western Yan that eventually led to Western Yan's destruction, Tuoba Gui sent a relief force, commanded by his cousin Tuoba Qian (拓拔虔) the Duke of Chenliu and the general Yu Yue (庾岳), but was unable to save Western Yan.