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Despite Later Yan's assistance of him and his status as a Later Yan vassal, Tuoba Gui began to secretly consider whether he could eventually conquer Later Yan. In 388, he sent his cousin Tuoba Yi the Duke of Jiuyuan to offer tributes to Murong Chui but also to observe the Later Yan court, to consider whether he would have eventual chance of attacking it. Murong Yi concluded that Murong Chui was growing old, and that his crown prince Murong Bao was incompetent—and that there were many potential claimants who would weaken Later Yan. This encouraged Tuoba Gui greatly in his eventual planning.