《资治通鉴·隋纪·隋纪五》
夏季，四月，癸亥，炀帝出临津关，渡过黄河，到达西平郡。布置军队，讲习武事，准备进攻吐谷浑。
夏，四月，癸亥，出临津关，渡黄河，至西平，陈兵讲武，将击吐谷浑。
In the summer, in the fourth month, on the day of gui hai (second day of the cycle), Emperor Yang exited Linjin Pass, crossed the Yellow River, and arrived at Xiping County. He proceeded to deploy troops and oversee military exercises in preparation for attacking the Tuyuhun.