In the second half of the 20th century, Sweden underwent a major expansion of hydropower. It was preceded by archaeological surveys, which discovered many previously unidentified settlement sites in the northern parts of the country. However, it was not long before the sites were drowned following the construction of dams to create hydropower reservoirs. Farms and villages were flooded and the people who lived there were forced to move away. In some places, special new communities were built to house those hydropower construction workers; when finished, the communities were abandoned and the workforce moved on to the next location. The expansion of hydropower echoed the ancient flood myths about how something old must perish for something new to be created.