Ancient Egyptian boats are defined as river-going vessels (in contrast with sea-going ships). Their use from late Prehistory through the Ptolemaic and Roman Periods included general transportation and travel, military use, religious/ceremonial use, and fishing. Depending on size and function, boats were built from papyrus or wood. The oldest form of propulsion was paddling, although there is some evidence for towing as well. Sailing was probably introduced towards the end of the late-Predynastic Period.