Question: Battle of the Barrier Forts was fought along the river that has what total length?
Sentence (from "Battle of Irtysh River"): The Battle of Irtysh River or Battle of Yexi River was a battle in 657 between Tang Dynasty general Su Dingfang and the Western Turkic Khaganate qaghan Ashina Helu during the Tang campaign against the Western Turks.
Relevant evidence: No