A rising tide lifts all boats, but in a surprising twist, ascending sea levels launched a flotilla of rafts or canoes on voyages from China to Taiwan around 5,000 years ago, a new study suggests.

At a time when rice farming dominated in other regions, the inundation of the Fuzhou Basin in southeastern China starting about 9,000 years ago led to the creation of a maritime culture that eventually took to the seas, says a team led by archaeologist Barry Rolett of the University of Hawaii in Honolulu.

Analyses of sediment cores extracted from the Fuzhou Basin indicate that, at that time, the kind of marshy areas that are needed for rice paddies disappeared under rising waters. What are hilltops in the region today shrank to islands no more than one mile across....