About 4, 000 years ago. Humans have technological advances. Represents the development of ideas with metal tools. In the first stage of the metal age, they know to melt the copper and Tin, which is the metal used is in the melting temperature. Later, the development of knowledge and technology, it's up to melt the iron. That required high temperature melting steel. About 4, 000 years. Humans bring copper mixed with tin alloy melts together become a pretend tools and better quality weapons made of terrazzo and approximately 3,200 years of technological development. Mankind invented the iron, which is the metal with the hardness and resistance thankwa of bronze tools and weapons. With a higher melting temperature to melt the bronze and then hit the metal iron, while still hot, as the shape that you want, because the steel used to make tools and utensils are suitable for agricultural tasks that require the use of a very strong and durable.
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