The development stage of human material culture marked by the use of bronzes. Bronze is an alloy of copper (pure copper) and tin or lead, and its melting point is between 700 and 900℃, which is lower than that of copper (1083℃). Bronze containing tin 10% has a hardness of 4.7 times that of copper and good performance. After the appearance of bronzes, it played an epoch-making role in improving social productivity. After the bronze age and before the early iron age, the age range in the world is about 4000 BC to the early AD. All parts of the world have entered this era. Bronzes were used in southern Iran, Turkey and Mesopotamia from 4000 to 3000 BC, and in Europe, India and Egypt from 3000 to 2000 BC. In Africa except Egypt and North Africa, bronze was used later, about no later than 65438 BC+0000 ~ early AD. Copper smelting centers did not appear in the United States until nearly 1 1 century.
In the Bronze Age, several important bronze casting industrial zones were formed in the world, which became the center of the formation of ancient human civilization. In some areas with developed ancient culture, the bronze age was adapted to the social form of slavery, such as Aegean Sea, Egypt, Mesopotamia, India, China and other countries and regions. At this time, slave countries flourished. However, there are also some areas that have directly transitioned to the Iron Age without going through the Bronze Age. In the Bronze Age, writing appeared in civilized areas.