What was the original name of Tolkien’s Mirkwood before it became known by that name?

Tolkien’s Mirkwood was originally called Greenwood the Great.

Greenwood the Great was a vast forest in Rhovanion, east of the Anduin. After the wizard Sauron established himself at Dol Guldur in the southern part of the forest, a growing shadow and evil influence changed its character. The forest became known as Mirkwood, reflecting its danger and darkness.

The Hobbit takes place after this transformation, so Bilbo and the company of Thorin encounter the forest as Mirkwood. They face confusing paths, giant spiders, and the Elvenking’s halls during their crossing. The forest’s changing name records a major shift in the history of the region.

After Sauron’s defeat in the War of the Ring, the forest was cleansed of his influence. Celeborn and Galadriel led efforts connected with its renewal, and the southern part was given the name Eryn Lasgalen, meaning “Wood of Greenleaves.” Eryn Lasgalen is therefore a later name, not the original one.