Han dynasty

The Han dynasty was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD) established by Liu Bang and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–206 BC) and a warring interregnum known as the Chu–Han Contention (206–202 BC), and it was succeeded by the Three Kingdoms period (220–280 AD). The dynasty was briefly interrupted by the Xin dynasty (9–23 AD) established by the usurping regent Wang Mang, and is thus separated into two periods—the Western Han (202 BC – 9 AD) and the Eastern Han (25–220 AD). Spanning over four centuries, the Han dynasty is considered a golden age in Chinese history, and had a permanent impact on Chinese identity in later periods. The majority ethnic group of modern China refer to themselves as the "Han people" or "Han Chinese". The spoken Chinese and written Chinese are referred to respectively as the "Han language" and "Han characters".

The Han emperor was at the pinnacle of Han society and culture. He presided over the Han government but shared power with both the nobility and the appointed ministers who came largely from the scholarly gentry class. The Han Empire was divided into areas directly controlled by the central government called commanderies, as well as a number of semi-autonomous kingdoms. These kingdoms gradually lost all vestiges of their independence, particularly following the Rebellion of the Seven States. From the reign of Emperor Wu (r. 141–87 BC) onward, the Chinese court officially sponsored Confucianism in education and court politics, synthesized with the cosmology of later scholars such as Dong Zhongshu.

The Han dynasty oversaw periods of economic prosperity as well as significant growth in the money economy that had first been established during the Zhou dynasty (c. 1050–256 BC). The coinage minted by the central government in 119 BC remained the standard in China until the Tang dynasty (618–907 AD). The period saw a number of modest institutional innovations. To finance its military campaigns and the settlement of newly conquered frontier territories, the Han government nationalised private salt and iron industries in 117 BC, creating government monopolies that were later repealed during the Eastern period. There were significant advances in science and technology during the Han period, including the emergence of papermaking, rudders for steering ships, negative numbers in mathematics, raised-relief maps, hydraulic-powered armillary spheres for astronomy, and seismometers that discerned the cardinal direction of distant earthquakes by use of inverted pendulums.

The Han dynasty had many conflicts with the Xiongnu, a nomadic confederation centred in the eastern Eurasian steppe. The Xiongnu defeated the Han in 200 BC, prompting the Han to appease the Xiongnu with a policy of marriage alliance and payments of tribute, though the Xiongnu continued to raid the Han's northern borders. Han policy changed in 133 BC, under Emperor Wu, when Han forces began a series of military campaigns to quell the Xiongnu. The Xiongnu were eventually defeated and forced to accept a status as Han vassals, and the Xiongnu confederation fragmented. The Han conquered the Hexi Corridor and Inner Asian territory of the Tarim Basin from the Xiongnu, helping to establish the Silk Road. The lands north of the Han's borders were later overrun by the nomadic Xianbei confederation. Emperor Wu also launched successful conquests in the south, annexing Nanyue in 111 BC and Dian in 109 BC. He further expanded Han territory into the northern Korean Peninsula, where Han forces conquered Gojoseon and established the Xuantu and Lelang commanderies in 108 BC.

After 92 AD, palace eunuchs increasingly involved themselves in the dynasty's court politics, engaging in violent power struggles between various consort clans of the empresses and empresses dowager. Imperial authority was also seriously challenged by large Taoist religious societies which instigated the Yellow Turban Rebellion and the Five Pecks of Rice Rebellion. Following the death of Emperor Ling (r. 168–189 AD), the palace eunuchs were massacred by military officers, allowing members of the aristocracy and military governors to become warlords and divide the empire. The Han dynasty came to an end in 220 AD when Cao Pi, king of Wei, usurped the throne from Emperor Xian.

According to the Shiji, after the collapse of the Qin dynasty the hegemon Xiang Yu appointed Liu Bang as prince of the small fief of Hanzhong, named after its location on the Han River (in modern southwest Shaanxi). Following Liu Bang's victory in the Chu–Han Contention, the resulting Han dynasty was named after the Hanzhong fief.

China's first imperial dynasty was the Qin dynasty (221–206 BC). The Qin united the Chinese Warring States by conquest, but their regime became unstable after the death of the first emperor Qin Shi Huang. Within four years, the dynasty's authority had collapsed in a rebellion. Two former rebel leaders, Xiang Yu (d. 202 BC) of Chu and Liu Bang (d. 195 BC) of Han, engaged in a war to determine who would have hegemony over China, which had fissured into Eighteen Kingdoms, each claiming allegiance to either Xiang Yu or Liu Bang. Although Xiang Yu proved to be an effective commander, Liu Bang defeated him at the Battle of Gaixia (202 BC) in modern-day Anhui. Liu Bang assumed the title of Emperor at the urging of his followers and is known posthumously as Emperor Gaozu (r. 202–195 BC). Chang'an (modern Xi'an) was chosen as the new capital of the reunified empire under Han.

At the beginning of the Western Han (traditional Chinese: 西漢; simplified Chinese: 西汉; pinyin: Xīhàn), also known as the Former Han (前漢; 前汉; Qiánhàn), thirteen centrally controlled commanderies—including the capital region—existed in the western third of the empire, while the eastern two-thirds were divided into ten semi-autonomous kingdoms. To placate his prominent commanders from the war with Chu, Emperor Gaozu enfeoffed some of them as kings.