During the Middle Ages, the Church that was the only real unifying power in Europe after the fall of the Roman Empire, did little to stimulate a spirit of adventure and inquiry. The geographical world concept was based strictly on the Bible. The Church frowned upon discoveries that might disprove accepted beliefs or inspire people to question age old doctrines. But in non-Christian Norway the people were hungry for land. There was little to cultivate among the steep mountains and countless lakes and fjords. Although coastal traffic was common among these seafaring people, they were unable to seek out new lands until they had ships suited to the open seas. This problem was solved with the development of high-powered, swift and graceful vessels that could be rowed as well as sailed. The long ships had a broad, flat-bottom construction that enable the crews to draw them ashore on both coast and river banks, making it possible for the Vikings to strike out from their fjords in search of land and booty. They were among the few inhabitants of the mediaeval world to venture out of their own territory.