In late September or October 249, Linghu Yu sent his subordinate Zhang Shi (張式) to contact Cao Biao and tell him that there were two popular sayings circulating in Dong Commandery (東郡; around present-day Puyang County, Henan): "A magical horse emerges from the White Horse River.
Pada akhir September atau Oktober 249, Linghu Yu mengirim bawahannya Zhang Shi (張式) untuk menghubungi Cao Biao dan mengatakan kepadanya bahwa ada dua ucapan populer yang beredar di Komanderi Dong (東郡; di sekitar yang sekarang County Puyang, Henan): "Seekor kuda ajaib muncul dari White Horse River.