The Huai River originates in Tongbai Mountain in Henan province.

It flows through southern Henan, northern Anhui, and northern Jiangsu, entering the Yangtze River at Jiangdu, Yangzhou.

Historically, the Huai River had entered the Yellow Sea at Yuntiguan ("Escalade Pass") through a broad and level lower course.

It was long used to irrigate the surrounding farmlands, and was the center of an extensive network of canals and tributaries.

Beginning in 1194, however, the Yellow River to the north repeatedly changes its course southwards to run into the Huai River, and will continue in this way until 1897.

The Mongol Empire's commanders in the Huai River area remain on the defensive, taking few major Song cities, although the regent Töregene and Güyük Khan order their generals to attack the Song.