函谷関
During the late Warring States period, Chu was increasingly pressured by Qin to its west, especially after Qin enacted and preserved the Legalistic reforms of Shang Yang. In 241 BCE, five of the seven major warring states–Chu, Zhao, Wei, Yan and Han–formed an alliance to fight the rising power of Qin. King Kaolie of Chu was named the leader of the alliance and Lord Chunshen the military commander. According to historian Yang Kuan, the Zhao general Pang Nuan () was the actual commander in the battle. The allies attacked Qin at the strategic Hangu Pass but were defeated. King Kaolie blamed Lord Chunshen for the loss and began to mistrust him. Afterwards, Chu moved its capital east to Shouchun, farther away from the threat of Qin.