4500~4000 years ago, the Longshan era was equivalent to the legendary Yao, Shun and Yu era. According to ancient documents, people began to smelt and cast bronzes at that time. Among the Longshan Age sites in the middle and lower reaches of the Yellow River and the Yangtze River, bronzes were found in dozens of sites after archaeological excavations.

Copper is the earliest metal copper used by human beings and one of the earliest metals discovered by human beings. It is a widely used metal and belongs to heavy metal. As early as prehistoric times, people began to mine open-pit copper mines and use the obtained copper to make weapons, tools and other utensils. The use of copper had a far-reaching impact on the progress of early human civilization.

China has a long history of using copper. About six or seven thousand years ago, China ancestors discovered and began to use copper. 1973, a semicircular copper chip was unearthed at Jiangzhai site in Lintong, Shaanxi Province, and was identified as brass.

1975, a bronze knife (about 3000 BC) was unearthed at the Majiayao cultural site in Linjia, Dongxiang, Gansu. This is the earliest bronze found in China at present, and it is the proof that China entered the Bronze Age.

Compared with West Asia, South Asia and North Africa, which entered the bronze age about 6,500 years ago, the bronze age in China came later.

China has an era when bronze and stone tools were used together, about 5500~4500 years ago. On this basis, China invented bronze alloy, which is the same as the development mode of bronze in the world.