《魏书·列传·卷二十三》
后来听凉州经商的胡人说，如果再向前行进两天，就能全部消灭蠕蠕。
后闻凉州贾胡言，若复前行二日，则尽灭之矣。
Later Emperor Xiaowudi heard from a Hu man who had been trading in Liang Prefecture that, if he had advanced two days’ journey further, he could have wiped out the Rouran.