The eastern remnant of the forests covering Middle-Earth in the
Elder Days, Fangorn forest, and possibly the Old Forest, were the
only remains of the forests of the Elder Days. Fangorn Forest was
certainly the only one with the Shepherds of the Trees still surviving.
Also called the Entwood, in Rohan, because of the Ents, who were
the Shepherds of the Trees. Fangorn Forest was an obviously old
forest, where there were some places that the original darkness
still had not been lifted according to Treebeard.