What name did Tolkien give the great forest later known as Mirkwood?

Tolkien named the great forest later known as Mirkwood Eryn Galen.

In Tolkien’s history of Middle-earth, the forest was originally called Greenwood the Great; Eryn Galen is its Sindarin name. After the arrival of the Necromancer, Sauron, in Dol Guldur, the forest became corrupted and was increasingly called Mirkwood.

Mirkwood is a major setting in The Hobbit. Bilbo and the Company of Thorin cross it after leaving Beorn’s house, encountering giant spiders and the Elvenking’s realm. The name Eryn Galen is therefore linked to the forest’s earlier identity, before the shadow of Dol Guldur changed its reputation and name.