"Weapons such as swords, spears, battle-axes, scimitars, shields, crossbows, and arrowheads were found in the pits.[28][37] Some of these weapons, such as the swords are sharp and were coated with a 10???15 micrometre layer of chromium dioxide and kept the swords rust-free for 2,000 years.[38][39][40] The swords contain an alloy of copper, tin, and other elements including nickel, magnesium, and co" . . . .