This early copper phase is commonly thought of as part of the Bronze Age, though true bronze, an alloy of copper and tin, was used only rarely at first. During the 2nd millennium the use of true bronze greatly increased; the tin deposits at Cornwall, England, were much used and were responsible for a considerable part of the large production of bronze objects at that time. The age was also marked by increased specialization and the invention of the wheel and the ox-drawn plow. From about 1000 BCE the ability to heat and forge another metal, iron, brought the Bronze Age to an end, and the Iron Age began.
