China has been an advanced country in terms of historical military technology. Infantry were armed with spears, bows, and in particular crossbows, a weapon in which the Chinese remained superior. It is widely thought that the famed Japanese sword was formed from the oldest straight sword designs from China. Most Chinese armour was scale which overlapped metal plates of different sizes and sewn into a cloth background. This armour is fairly light and flexible but lacked protective strength. The stirrup became widespread in China around the fifth century. It is connected with the development of armoured cavalrymen, mounted on an armoured horse. Although cavalry were a large part of the Chinese ruling class, China did not move into feudalism as Europe did.