River Andahar
From Tar Valon Library
A similar entry appears in the Wheel of Time Companion confirming the information available in the main story arc.
The Andahar is a river with its source in the Mountains of Mist, in either Tarabon or Almoth that flows through Tarabon and eventually through Tanchico, which lies on either side and into the Aryth Ocean. In earlier times, it formed the border between Balasun and Elan Dapor.
(Reference, The World of Robert Jordan's "The Wheel of Time"),