Shetland is an archipelago off the northeast coast of Scotland. The islands lie to the northeast of Orkney, 170 miles from the Faroe Islands, and form part of the division between the Atlantic Ocean to the west and the North Sea to the east. The total area is approximately 566 square miles. Shetland has been populated since at least 3400 BC. The early people subsisted on cattle-farming and agriculture. During the Bronze Age, around 2000 BC, the climate cooled and the population moved to the coast. During the Iron Age, many stone fortresses were erected, some ruins of which remain today. Due to the practice, dating to at least the early Neolithic, of building in stone on the virtually tree-less islands, Shetland is extremely rich in physical remains of all these periods.