What is bronze?
September 2016 - Bronzesmiths make bronze by melting two different metals and mixing them. The two metals are copper and tin. Copper, by itself, is too soft to make tools of. (Have you ever had a copper bracelet? It dents every time you knock your hand on a door). Tin is too brittle: it breaks too easily. But if you mix a little tin into the copper, it becomes bronze, which is much harder and at the same time less brittle. It is more useful for tools and also better for making statues. (Early on, people tried mixing copper with other things like lead and arsenic, but tin works best.)
Etruscan greaves (Vatican Museum, Rome)
about 600 BC
When West Asian smiths first began to make bronze, about 3500 BC, it was very expensive. Mostly people used bronze for weapons and armor. You could make a much better sword out of bronze than out of stone or wood. Bronze swords were lighter and sharper. Still, they weren't strong enough to cut with the side of the blade: you had to use bronze swords mainly to stab people, or your sword would break. Bronze armor was stronger and lighter than the leather and wood armor soldiers had worn before. Everybody wanted it for war. By 3000 BC, Central Asians and Harappans in India were using bronze. Around 2000 BC, Indo-Europeans spread the use of bronze to Europe and China. The Hyksos encouraged Africans in Egypt and Sudan to use more bronze around 1700 BC.
But soon Chinese and West Asian artists also began to use bronze to make bronze statues. As with the weapons, bronze is lighter than stone, and you can make statues in different poses with bronze than you can with stone. To get these bronze statues, the artists invented lost-wax casting.
By 900 AD, Ife and Hausa people in West Africa were also using bronze alongside of iron. But after that, when new people in the Caribbean or the Pueblos or Brazil learned how to work metal, they went straight to using iron, and nobody used much bronze anymore.
When bronze gets old, and the air touches it, it corrodes (like iron rusting) and turns green, like these Etruscan greaves (leg armor). Once bronze got old and corroded, people usually sold it to a bronze-smith to melt down and recycle into new bronze things - that's why we don't have very much ancient bronze.