The Banas River is one of the many rivers of Tortall. It branches off of the River Tellerun and the Halseander. The land between the Banas and the Halseander is fertile marshland known as War Gorge Marsh. It is one of three rivers to make up the Three Rivers Province of Tortall.
Pounce knows differently: the land of War Gorge Marsh was once inhabited by the Ianto clan, members of the fearsome humanoid race known as the Ysandir. They were involved in a brutal war with the dragons, specifically the Spearflame clan. They used the marshland to build trenches and later, those trenches flooded with water from the aquifers below.