The argument could be made that some modern Sámi never settled. A small amount of them still live in northern Fennoscandia as reindeer herders.

I think you can make the case that the people of St kilda lived primarily as gatherers. On this small Scottish island, huge bird colonies exist. The people would gather eggs, feathers, and birds by the hundreds for food, fuel, and sale. While they had small scale agriculture, most of their sustenance came from hunting /gathering. The population left the island in 1930.