<P> The settlement of the north continued up to Qin Shi Huang's death in 210 BC, upon which Meng Tian was ordered to commit suicide in a succession conspiracy . Before killing himself, Meng Tian expressed regret for his walls: "Beginning at Lintao and reaching to Liaodong, I built walls and dug moats for more than ten thousand li; was it not inevitable that I broke the earth's veins along the way? This then was my offense ." </P> <P> Meng Tian's settlements in the north were abandoned, and the Xiongnu nomads moved back into the Ordos Loop as the Qin empire became consumed by widespread rebellion due to public discontent . Owen Lattimore concluded that the whole project relied upon military power to enforce agriculture on a land more suited for herding, resulting in "the anti-historical paradox of attempting two mutually exclusive forms of development simultaneously" that was doomed to fail . </P> <P> In 202 BC, the former peasant Liu Bang emerged victorious from the Chu--Han Contention that followed the rebellion that toppled the Qin dynasty, and proclaimed himself Emperor of the Han dynasty, becoming known as Emperor Gaozu of Han (r . 202--195 BC) to posterity . Unable to address the problem of the resurgent Xiongnu in the Ordos region through military means, Emperor Gaozu was forced to appease the Xiongnu . In exchange for peace, the Han offered tributes along with princesses to marry off to the Xiongnu chiefs . These diplomatic marriages would become known as heqin, and the terms specified that the Great Wall (determined to be either the Warring States period Qin state wall or a short stretch of wall south of Yanmen Pass) was to serve as the line across which neither party would venture . In 162 BC, Gaozu's son Emperor Wen clarified the agreement, suggesting the Xiongnu chanyu held authority north of the Wall and the Han emperor held authority south of it . Sima Qian, the author of the Records of the Grand Historian, describes the result of this agreement as one of peace and friendship: "from the chanyu downwards, all the Xiongnu grew friendly with the Han, coming and going along the Long Wall". However, Chinese records show that the Xiongnu often did not respect the agreement, as the Xiongnu cavalry numbering up to 100,000 made several intrusions into Han territory despite the intermarriage . </P> <P> To Chinese minds, the heqin policy was humiliating and ran contrary to the Sinocentric world order like "a person hanging upside down", as the statesman Jia Yi (d . 169 BC) puts it . These sentiments manifested themselves in the Han court in the form of the pro-war faction, who advocated the reversal of Han's policy of appeasement . By the reign of Emperor Wu (r . 141--87 BC), the Han felt comfortable enough to go to war with the Xiongnu . After a botched attempt at luring the Xiongnu army into an ambush at the Battle of Mayi in 133 BC, the era of heqin - style appeasement was broken and the Han--Xiongnu War went into full swing . </P>

Who built the great wall of china and why was it built