《汉书·志·五行志下之上》
这一年匈奴攻入上郡、云中，烽火通到长安，派遣三位将军驻扎边境，三位将军驻扎京师。
是岁，匈奴大入上郡、云中，烽火通长安，遣三将军屯边，三将军屯京师。
In that year, the Xiongnu invaded Shangjun and Yunzhong, the beacon fires reaching Chang'an; three generals were dispatched to station themselves at the border, and three generals to station themselves in the capital.