Boatmaking and navigation has been important to man for thousands of years - for communication, transport, and fishing. There is much evidence of dugout canoes from Mesolithic times onward, the earliest being at Perth and in Denmark. Neolithic people used skiffs as well as dugout canoes. Plank boats appeared in the Middle Bronze Age. In the Roman period, boats started being made with nails. Seagoing vessels existed, but there is not much evidence except for skin boats, like the Irish curragh. Classical writers describe plank-built boats with sails of leather on the Atlantic before the Romans arrived. Full documentation begins only with the Vikings. The Americas have yielded two regional pre-conquest types of craft: the reed caballitos of the Peruvian coast and Lake Titicaca, and the seagoing balsa rafts from the Gulf of Guayaquil. The oldest boat in Europe was found on the Tay. It is a dugout canoe used by Maglemosian immigrants from Denmark 10,000 years ago.