Tol Fuin was the largest of isles with Tol Morwen and Himling being relatively smaller. Himling and Tol Fuin were relatively close to one another, while Tol Morwen was about one-hundred and fifty miles southwest of the other two islands.
The Western Isles had not always been islands and were once significant and well-known places in Beleriand before it sunk under the waves at the end of the First Age. Tol Morwen was the location of the grave of Morwen Eledhwen, the wife of Húrin Thalion and mother of Túrin Turambar and the Stone of the Hapless. Himling had been Himring, the realm of the eldest of the Sons of Fëanor Maedhros. Tol Fuin was a part of the highlands of Dorthonion that were later renamed Taur-nu-Fuin.
After the War of Wrath and the loss of the Beleriand, the Western Isles were refugee locations where for a time many of the Noldor, Sindarin elves, and the Edain stayed until departing for the Undying Lands and Númenor. The Western Isles were not known to have every been inhabited permanently for the rest of the Second Age, the Third Age, and beyond.
- The Atlas of Middle-earth pgs. 38, 52-3