Ancient Greek technology developed at an unprecedented speed during the 5th century BC, continuing up to and including the Roman period, and beyond. Inventions that are credited to the ancient Greeks such as the gear, screw, bronze casting techniques, water clock, water organ, torsion catapult and the use of steam to operate some experimental machines and toys. Many of these inventions occurred late in the Greek period, often inspired by the need to improve weapons and tactics in war. Roman technology is the engineering practice which supported Roman civilization and made the expansion of Roman commerce and Roman military possible over nearly a thousand years. The Roman Empire had the most advanced set of technology of their time, some of which may have been lost during the turbulent eras of Late Antiquity and the Early Middle Ages. Roman technological feats of many different areas, like civil engineering, construction materials, transport technology, and some inventions such as the mechanical reaper went unmatched until the 19th century.