Bronze Age: c. 4000 to 1000 BCE, an era characterized by the importance of bronze, a tin and copper alloy, used for making weapons and tools. It was preceded by the Neolithic Period and was followed by the Iron Age. The start of this era varies from location to location as some civilizations discovered bronze and its many uses before others. During this era, writing was invented and civilizations saw other great developments in their culture, all due to the practicality of bronze.
Craig, Albert, et al. The Heritage of World Civilization. 2nd edition. Combined vol. Upper Saddle River, N.J.: Prentice Hall, 2005.