《北史·本记·卷一》
五年春正月，道武帝听说姚兴准备进犯边境，便大举挑选吏卒，诏令并州各军储藏粮食放在平阳乾壁。
五年春正月，帝闻姚兴将寇边，庚寅，大简舆徒，诏并州诸军积谷于平阳乾壁。
In the first month of spring of the fifth year, Emperor Daowu heard that Yao Xing was going to invade the country and prepared military personnel on a large scale, ordering grain to be stored in Pingyang Qianbi from various military posts in Bingzhou.