Shan Yu was among the villains abducted by Frollo's Nobody and to be converted into a cycle visionary. Due to his strong heart and powerful will, Shan Yu was able to break free of the Xehanort Heart Shard that had been lodged within his heart and actually provided a difficult challange to Young Xehanort in combat. But because of the younger keyblade master's greater learned experience in Keyblade and Time Skills, Shan Yu inevitably lost, and was slain by the Master Xehanort's dark keyblade, splitting him into a powerful Heartless Lord and Berserker Nobody, both filled with rage and anger in their beings, even more so than Scroop's Heartless.
Shan Yu's Heartless was thus let loose on the Land of Dragons, and even on it's own without Nightwalkers or Berserkers, it created mass carnage and destruction in its path. The combined force of the Lougers, Mulan, and General Li Shang finally brought this beast down, giving Sora enough room to slay the Heartless Lord and put its heart back in the Berserker Nobody to retransform it back into the original Shan Yu. However, he only gave an angry threat to never speak of this event to anyone or himself ever again. He was soon met with the Emperor of China, demanding the Hun Leader to leave while he still has an oppurtunity to do so under threat of his imperial guards. Knowing fully well that this wasn't a battle he was able to win anyway, Shan Yu accepted and fled back to Hollow Bastion with Hayabusa in tow.