“轻车”、“骑士”、“材官”、“楼船”是秦汉时期的四大兵种。“轻车”即率兵，“骑士”即骑兵，“材官”为步兵，“楼船”为水兵。由于车战已衰落，秦汉时期，车兵的数量越来越少，一般情况下与步兵合编。骑兵和水兵依靠马政和造船业的发展，数量也有限。因此，秦汉时期步 “Light car”, “knight”, “officer”, “building ship” is the Qin and Han dynasties four branches. The “light car” means the soldier, the “knight” the cavalry, the “timber officer” as the infantryman and the “building boat” as the sailor. As the car battle has declined, Qin and Han Dynasties, fewer and fewer car soldiers, under normal circumstances and infantry co-editor. Cavalry and sailors rely on the development of Ma Zheng and the shipbuilding industry, the number is limited. Therefore, the Qin and Han Dynasties step