Tin is an essential
metal in the creation of tin
bronzes and its acquisition was an important part of
ancient cultures from the
Bronze Age onwards. Its use began in the
Middle East and the
Balkans around 3000 BC. Tin is a relatively rare element in the
Earth's crust, with about 2
parts per million (ppm), compared to
iron with 50,000 ppm,
copper with 70 ppm,
lead with 16 ppm,
arsenic with 5 ppm,
silver with 0.1 ppm, and
gold with 0.005 ppm . Ancient sources of tin were therefore rare, and the metal usually had to be traded over very long distances to meet demand in areas which lacked tin deposits.