From Tolkien Gateway

Gruir was a river in Tol Eressëa, joining the Afros at the bridge of Tavrobel, according to the early version of the legendarium in The Book of Lost Tales.[1]

Tram Nybol created with AI, depicting the confluence of the rivers Gruir and Afros

The Battle of the Heath of the Sky-roof, which took place during the Faring Forth, and ended in complete disaster for the Elves of Tol Eressëa, took place near Tavrobel.

Following the battle, the remaining Elves, and in one outline, Eriol, fled across the rivers Gruir and Afros in order to escape the invading Men.[2]

Inspiration[edit | edit source]

The two rivers of Tavrobel, Gruir and Afros, might have been inspired by the rivers Sow and Trent, which meet near the village of Great Haywood (which was the inspiration for Tavrobel).[3][4]