2. Before the invention of iron smelting technology, people could only make tools with bronze, which was much better than tools made with stones and sticks. Therefore, in the international history, a nation can only be called into the era of civilization if it has mastered bronze technology. At that time, people used bronze to make farm tools, tools, weapons, household utensils, etc. After the invention of iron, bronze was only used to make sacrificial utensils.
3. In Dayu era, Jiuding was cast as a symbol of Kyushu, and since then it has been handed down as a symbol of political power. Although Japan and South Korea were affected, they did not have such feelings as China.