The Gap of Dunloe was started and hewn two million years ago and is one of the finest examples of a glaciated valley in western Europe. It is a narrow pass in the McGuillycuddy Reeks between the Purple Mountain and the Bull Mountain. Killarney's ice age began two million years ago when the great glaciers churned through the mountains and ended about 10,000 BC. As ice and snow slowly pushed northward through the Killarney Valley, they gave the mountains their jagged edges, and the Gap was formed. The name Dunloe comes from the Gaelic Dun Loich, meaning the stronghold of Loich, the first leader of an ancient tribe called the Fir Bolg, the men of bags, who ruled before the Tuatha de Danaan and the Milesians.