Fangorn Forest, the East End of the great forests of the Second Age (somewhat conjectural)

Until the later Second Age, most of the lands of Eriador had been thickly forested. In those days the woods stretched from Ered Luin (the Blue Mountains, or Mountains of Lune), running southwards and eastwards across the lands where the Shire would one day lie, to meet the Misty Mountains in the east. One outlying patch of forest even succeeded in growing beyond the barrier of the Misty Mountains, a region that would eventually become known as Fangorn Forest. During the latter half of the Second Age, most of the great western forest was felled, but while the trees still stood Fangorn had been merely an easterly outgrowth of that vast wood, and so Treebeard remembered it simply as the East End.