After the collapse of the Qin Dynasty, Chu-Han Contention broke out between Liu Bang(the first emperor of the Han Dynasty) and Xiang Yu (the overlord of Western Chu), who fought against each other for the sovereignty. The battle lasted for approximately four years from 206 B.C. to 202 B.C.

In October, 206 B.C., Liu Bang commanded his troops to exterminate the Qin Dynasty and later he claimed the throne in Guanzhong area (plain area in central Shaanxi). Soon after that, Xiang Yu along with his armies entered the area in the hope of annihilating Liu’s administration and made himself the king. Being aware that he could not outweigh Xiang Yu at the moment, Liu Bang came to Hongmen (northeast of Shaanxi today) in person in order to reach a compromise with Xiang Yu and gave Guanzhong up to him. Before long, Xiang Yu declared Overlord of Western Chu there, and bestowed the title of Prince of Han on Liu Bang. Besides, he conferred another dozen of official titles on other followers to restrain Liu Bang’s power. Meanwhile, Liu Bang strengthened his force in his own territory with great efforts and enhanced the military training, getting prepared to contend with Xiang Yu at any time. After a period of time, Liu Bang’s troops took Guanzhong area again while Xiang Yu’s armies were at war with other forces. Hence the prologue of the Chu-Han war unfolded.

In April, 205 B.C., Chu and Han armies launched a decisive battle in Peng City, and the Han failed. From then on, the two sides were in the state of long-term confrontation and many wars broke out successively. During that period, Xiang Yu was not good at appointing talented people, and was not inclined to adopt others' suggestion as well. Consequently, many military strategies were inappropriate to carry on. Gradually he lost people’s support. At the same time, however, Liu Bang won Xiao He and Han Xin’s assistance and common people’s heart. He deployed forces in wise way and gradually gained advantages in military aspect.

In 204 B.C., Xiang Yu was forced to compromise with Liu Bang and put forward some suggestions to him. They reached an agreement to take Honggou as the dividing line of Chu and Han: the west of it belonged to Han, while the east part belonged to Chu. Subsequently Xiang Yu led on his armies to withdraw eastward. But Liu Bang and his army chased the withdrawing troop in full sail. In December, 202 B.C., Xiang Yu was trapped in Gaixia, and the whole Chu army suffered a great loss. Xiang Yu brought forth a few soldiers out of the trap and arrived at the Wu River, but still ended up with a failure. Ashamed of facing up to the people in his hometown, Xiang Yu committed suicide by cutting the throat on the side of the Wu River. Therefore, Chu-Han Contention came to an end with the winning of Liu Bang’s Han army.

In 202 B.C., after the Chu-Han contention ended, Liu Bang established the Han Dynasty and made Chang’an its capital. He is known as Han Gaozu in the history of China.