When the first immigrants to what was 10 000 years later to become Sweden reached these shores, they were hunters and gatherers. This was far from unique, as the same way of life dominated Homo Sapiens's experience for its entire, if brief, sojourn on Planet Earth. They followed the trails of their game of choice, mainly reindeer, and traversed the land bridge then straddling what was to become the Kattegatt Sea between Denmark and Sweden.
The reason for Homo Sapiens's late arrival in the north was the two mile thick sheet of ice that covered the entire Scandinavian peninsula during the last Ice Age, which made efforts of human colonization futile. As the ices melted away a land of tundra and low, hardy vegetation was revealed. Great parts of the Scandinavian landmass was still out of reach, however, as the mass of ice had pushed the land far beneath the ocean waves. Gradually, these parts began to rise again out of the waves in a process which continues to this day; the post-glacial rebound.