Complex sentence: Coigach is the ancient (but still used) name for the area north of Ullapool, in Wester Ross in North-West Scotland, which abuts the area known as Assynt further to the north.
Split into simpler sentences: Coigach is the ancient name for the area north of Ullapool, in Wester Ross in northwest Scotland. This abuts the area known as Assynt further to the north.