伏允
Sometime before 634, Murong Fuyun appeared to make an overture toward peace—by sending an emissary to offer tributes to Emperor Taizong—but even before the emissary left, Tuyuhun forces attacked and pillaged Shan Prefecture (鄯州, in modern Haidong Prefecture, Qinghai). When Emperor Taizong sent emissaries to rebuke Murong Fuyun and summoned Murong Fuyun to Chang'an to meet him, Murong Fuyun refused, but responded by requesting that a Tang princess be given to his son, the Prince of Zun, in marriage. Emperor Taizong agreed, but ordered that the Prince of Zun personally arrive in Chang'an to marry the princess. When the Prince of Zun failed to do so, Emperor Taizong cancelled the marriage. Meanwhile, Murong Fuyun also attacked Lan and Kuo (廓州, also in modern Haidong) Prefectures and detained the Tang emissary Zhao Dekai (趙德楷). Emperor Taizong sent a number of emissaries to Tuyuhun to discuss the matter and also summoned Tuyuhun emissaries and personally had discussions with them. Murong Fuyun still did not relent.