During the final years of the Qin Dynasty, the Han and Chu forces were locked in a prolonged stalemate. The soldiers, exhausted from endless marches and battles, grew weary and restless.
King Liu Bang of Han sent an envoy to persuade King Xiang Yu of Chu, saying, "Your Majesty and the King of Han both received orders from King Huai of Chu and once swore brotherhood. Now the King of Han has vast territory, numerous troops, and ample supplies, while Your Majesty's soldiers are weary and provisions are nearly exhausted. Under these circumstances, the King of Han, in his benevolence, has sent me to negotiate a truce with Your Majesty."
Xiang Yu was about to erupt in anger, but then he reconsidered, realizing the Han envoy's words were true and not a fabrication. He declared in a clear voice, "I am a man of great literary and martial prowess, while Liu Bang is nothing but a cunning trickster with petty skills. In the past, I spared his life several times. Now that Liu Bang cannot hold out and seeks peace with me, I will spare him once more—let us negotiate a truce!"
Thus, the Central Plains were split in two: the land west of the Guandu River belonged to Han, while the land east of the Guandu River belonged to Chu.
After the Battle of Gaixia, Han King Liu Bang wanted to retreat westward to rest and recover. His strategists Zhang Liang and Chen Ping advised him, "The empire is now split into three, and Your Highness already controls two-thirds of it. Moreover, you follow Heaven's will, and all the feudal lords have submitted to us. Although Chu King Xiang Yu is domineering, his troops are exhausted and his supplies are depleted. This is a golden opportunity granted by Heaven to defeat Xiang Yu! Rather than leading the army back to Shu, seize this rare chance to annihilate him once and for all. If you let Xiang Yu go now, allowing him to rebuild his army and stockpile grain until he is fully prepared, he will surely come back to harass us. Wouldn't that be like raising a tiger only to be bitten by it later?"
Emperor Liu Bang of Han followed the counsel of his advisors Zhang Liang and Chen Ping, ordering the generals Han Xin and Peng Yue to join forces and strike against Chu, forcing the Hegemon-King Xiang Yu to take his own life at the Wu River.
"Raising a tiger invites disaster" means keeping a tiger brings future calamity. It later describes sheltering or indulging an enemy, leaving trouble for oneself.
Source: *Records of the Grand Historian*, "Biography of Xiang Yu"
Meaning of the Idiom: Later, the Chinese idiom "养虎遗患" came to describe keeping a tiger brings future calamity.