Tarwin's Gap is the northernmost pass through the Spine of the World, located in the valley between the Mountains of Dhoom and the Spine. It was one at the edge of Malkier, but since Malkier fell, it has been at the base of the Blight (TWoRJTWoT, Ch. 15). It has been the site of many confrontations with Shadowspawn (TEotW, Ch. 46).
Over the years, many lands have sent men to fight in the Blight and Coming Home From Tarwin's Gap is a popular song in the Two Rivers and Andor itself (TEotW, Ch. 31; Ch. 46). When Rand went to The Eye of the World, an immense gathering of Trollocs and Myrddraal threatened to overwhelm the Shienaran's at Tarwin's Gap, outnumbering them ten to one (TEotW, Ch. 46), and it was only his direct intervention that prevented this (TEotW, Ch. 51).