In 215 BC, Qin Shi Huangdi ordered General Meng Tian to set out against the Xiongnu tribes, situated in the Ordos region, and establish a frontier region at the Ordos Loop. Believing that the Xiongnu were a possible threat, the emperor launched a preemptive strike against the Xiongnu with the intention to expand his empire.
In 215 BC, General Meng Tian succeeded in defeating the Xiongnu and driving them from the Ordos region, then he seized their homeland. After the catastrophic defeat at the hands of General Meng Tian, the Xiongnu leader Touman was forced to flee far into the Mongolian Plateau. As a result of the northward expansion, the threat that the Qin empire posed to the Xiongnu ultimately led to the reorganization of the many tribes into a confederacy.
General Meng Tian was instructed to secure the frontier with a line of fortifications, which would become known as the Great Wall of China.Fusu (Prince of Qin) and General Meng Tian were stationed at a garrison in Suide and soon began with the construction of the walled defenses, which would be connected with the old walls from the Qin, Yan, and Zhao states. The Qin walls ran from Liaodong to Lintao, thus enclosing the conquered Ordos region.
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