The Zhao state in North China bordered areas inhabited by nomadic tribes described as the Hu (胡) people.
[3] In 307 BC, he made a decision to reform the Zhao military by making it adapt many of the traits that nomadic tribes had.
[5] General Li Mu was appointed to oversee the borders and would frequently stay at Dai and Wild Goose Gate.
[7] Li made a decree stating that whenever the Xiongnu conduct raids, soldiers are to light the beacons and everyone is to retreat to the fortifications.
King Huiwen replaced Li and the next year, every time the Xiongnu came the new general would let the soldiers attack them.
[7] Li then prepared a large army that consisted of 1,300 war chariots, 13,000 cavalry, 50,000 infantry and 100,000 archers.
[7] The Xiongnu Chanyu, hearing about this significant victory, decided to launch a large scale invasion into Zhao.
[6][7] Since Zhao no longer had to worry about threats from the north, it could focus its attention on fighting the other states in the central plains.
In a one-shot manga that Yasuhisa wrote before publishing Kingdom, it details the preparations Li made for the war.