The spatha was a type of straight and long sword, measuring between 0.75 and 1 m (30 and 39 in), in use throughout first millennium AD Europe, and in the territory of the Roman Empire until about 600 AD. Later swords from 600 AD to 1000 AD, like the viking swords, are recognizable derivatives, though they are not truly spathae. The spatha was used in war and in gladiatorial fights. The spatha of literature appears in the Roman Empire in the first century AD as a weapon used by presumably Germanic auxiliaries and gradually became a standard heavy infantry weapon, relegating the gladius to use as a light infantry weapon. The spatha apparently replaced the gladius in the front ranks, giving the infantry more reach when thrusting. While the infantry version had a long point, versions carried by the cavalry had a rounded tip that prevented accidental stabbing of the cavalryman's foot. Archaeologically many instances of the spatha have been found in Britain and Germany. It was used extensively by Germanic warriors. It is unclear whether it came from the Pompeii gladius or the longer Celtic swords, or whether it served as a model for the various broadswords and Viking swords of Europe. The spatha remained popular throughout the Migration Period. It may have evolved into the knightly sword of the High Middle Ages from about 1100 AD, but the large number of sword types that appeared during the period make it difficult to establish links. The details of their manufacture remain mostly unknown.