Han–Xiongnu wars

The Han–Xiongnu wars or Sino–Xiongnu wars, were a series of military conflicts fought from 133 BC to 89 AD between the agrarian Chinese Han dynasty and the nomadic pastoralist Xiongnu confederacy, although extended conflicts can be traced back as early as 200 BC and as late as 188 AD. The Chinese civilization initially clashed with the Inner Asian steppe nomad tribes (then collectively known as Di) that would later become the Xiongnu during the Warring States period, and various northern states built elongated fortifications (which later became the Great Wall of China) to defend against raids down from the Mongolian Plateau. The unified Qin dynasty, who conquered all other states under Qin Shi Huang, dispatched Meng Tian in 215 BC in a successful campaign to expel the Xiongnu from the Ordos region (which was often used as a staging area to threaten Qin's Guanzhong heartland). However, the subsequent civil war following the Qin dynasty's collapse gave the Xiongnu confederacy, which were then unified into a large nomadic empire under Modu Chanyu, the opportunity to reinvade the Ordos region. After the Han dynasty was established in 202 BC, Emperor Gaozu tried to fight off Xiongnu invasions but had himself trapped in an ambush during the Battle of Baideng, and a truce was negotiated by bribing Modu's wife, thus ending the first Han–Xiongnu conflict. Decades of de jure peace then followed with the Chinese implementing marriage alliances to appease the Xiongnu, who still routinely raided Chinese borderlands. However, starting from the reign of the seventh Han sovereign, Emperor Wu, the foreign policy of the Han dynasty began to change from being relatively passive to using a proactive strategy seeking to permanently remove the northern threat. The tension fully escalated in 133 BC when the Han army unsuccessfully tried to ambush Xiongnu raiders...