Inside the actual cooperation area of Archipelago National Park, no Stone Age settlements have been found so far, but there are about forty burial mounds from the Bronze Age and Iron Age. Two fort islets from the prehistoric times have also been recognised in the archipelago, possibly dating back to the Iron Age. Trade, handcraft and navigation were practiced already in the early times in addition to the basic sources of livelihood. Sailing began in the whole of the Baltic Sea region latest in the Bronze Age. The southwestern archipelago became a part of the northern Baltic Sea region cultures, which had common means of livelihood, use of metals, and burial customs. The present National Park area became inhabited in the Iron Age (500 BCE-1150 CE). Many ancient remains of the Iron Age settlements have been found in the National Parks cooperation area. Pollen analysis has shown that the agriculture in the coast has been continuous since the Iron Age until these days. The most characteristic antiquities of the archipelago are relics from the historic times, from the end of the Iron Age until the 18th and 19th century. These immovable relics are also protected by the Antiquities Act.