The Han dynasty named China and invented paper, seismometers, and silk roads
Liu Bang's Han dynasty ruled from 202 BC to 220 AD, interrupted only by Wang Mang's Xin dynasty from 9 to 23 AD. Modern Chinese call themselves Han people and their language Han. Emperor Wu's campaigns opened the Silk Road and pushed the Xiongnu beyond the Gobi.
After defeating Xiang Yu at Gaixia in 202 BC, Liu Bang became Emperor Gaozu and made Chang'an the capital. Semi-autonomous kingdoms covered two-thirds of the empire until the Rebellion of the Seven States in 154 BC led to reforms limiting royal power by 145 BC. Confucianism gained official court sponsorship under Emperor Wu from 141 BC, synthesized with Dong Zhongshu's cosmology.
The Xiongnu defeated Han forces at Baideng in 200 BC, forcing marriage-alliance tribute until Wu reversed policy in 133 BC. Campaigns culminated at Mobei in 119 BC when Huo Qubing and Wei Qing drove the Xiongnu court north of the Gobi. Zhang Qian's missions from 139 to 125 BC linked China to Central Asia and eventually Rome. By 60 BC imperial authority extended over the Tarim Basin oases through a western protectorate.
Technological advances included papermaking, ship rudders, negative numbers, raised-relief maps, and inverted-pendulum seismometers that pointed toward distant earthquakes. Wu nationalized salt and iron in 117 BC to fund expansion. A census in 2 AD registered 57,671,400 people. After 92 AD eunuchs and warlords fractured the court; the Yellow Turban Rebellion and Cao Pi's usurpation in 220 AD ended the dynasty. Expansion ran south and east as well: a naval campaign took Nanyue, covering today's Guangdong, Guangxi and northern Vietnam, in 111 BC, the Dian Kingdom of Yunnan fell in 109 BC, and Gojoseon on the Korean Peninsula followed in 108 BC. Coins minted by the court in 119 BC stayed China's standard currency until the Tang dynasty. The dynasty's name itself comes from Hanzhong, the small fief on the Han River that Xiang Yu first granted Liu Bang.
Source: Han dynasty
