The area around Jämjö was in old times an area of importance in Blekinge. Lots of ancient remains on the hills show that people have lived here since the Stone Age.
Near the bay of Hallarum is an old farmer's harbour. Remains show it was used already in the Viking Age. At this time the harbour was protected by a wooden palisade beneath the water, probably the ancient castle nearby was built for the same reason namely to protect the harbour.
On Store backe (The big hill) near the north beach is a large grave field from the same period.