The Barrow Run river rises in the Hungry Mountains in the heart of Virlych county in south-eastern Ustalav. It runs in an easterly direction for over twenty miles before turning northwards to become the border between the counties of Virlych and Amaans. After some fifteen miles the Barrow Run, along with the county border, turns to a north-easterly direction, eventually joining the Orphield River as a tributary. For its last fifteen miles, the Barrow Run becomes the county border between Amaans and Canterwall. In total, the river is about sixty miles long.
The Barrow Run, along with the Mesmos River, form a boundary between different weather patterns in the Hungry Mountains and Virlych: to the west of these two rivers, angry, purple clouds adorn the mountain peaks in some way controlled by the malevolent spirit of the Whispering Tyrant; to the east, violent storms wrack the mountains.