RUSSIA: Today, Zhokov Island lies more than 300 miles north of mainland Russia, far beyond the Arctic Circle. Around 9,000 years ago, though, when it was still attached to Siberia, the area was home to a surprisingly well-connected and mobile community. Obsidian tools discovered on the island came from a source more than 900 miles away. It is believed that Mesolithic Zhokovians traveled by dogsled to acquire the material, although it is unclear whether they trekked the entire way or met obsidian traders somewhere along the route.