The Bronze Age refers to a period of time in prehistoric societies where metallurgy had advanced to the point of making bronze — an alloy of tin and copper — from natural ores, but not yet to the point of the systematic production of iron (the Iron Age). This period is more advanced than the Stone Age, in which artifacts and tools are largely made from carved stone. Stone, Bronze, and Iron make up the traditional three-age system for classifying prehistoric cultures. In some areas of the Earth, like Africa, certain groups went straight from the Stone Age to the Iron Age, and rare groups, such as isolated Amazonian tribes in Brazil, have not yet progressed past the Stone Age.
This period primarily took place between 3500 BC and 1200 BC, and it is traditionally divided into the Early (c.3500-2000 BC), Middle (c.2000-1600 BC), and Late (c.1600-1200 BC) ages, with progressively more sophisticated metallurgy, culminating in the discovery of ironworking.
The Bronze Age began 5,500 years ago in the present-day areas of Turkey, Iran, and Iraq, which was also the cradle of human civilization. By this time, permanent settlements were already a few thousands years old, but it took time for these early people to discover the potential of metallic ores. The birthplace of metallurgy is usually taken to be Anatolia, Turkey.
The Indian Bronze Age began in 3300 BC with the Indus Valley civilization. In China and southeast Asia, it began around 2100 BC. Throughout Europe, people started using this metal between 2100 BC and 2000 BC or so, with sophisticated civilizations rising throughout the 2nd millennium BC.
This period of development was important to mankind because it allowed people to create more durable tools and artifacts for productive use. Bronze is preferable to stone for a wide variety of applications — whether someone is making a knife, an axe, armor, pottery, or artwork, bronze is harder and longer-lived. A more durable capital base enhances the potential for sustained economic activity, but also warfare.
During this age, much of humanity was segmented into thousands of warring tribes. Small nations did exist, but it would be many centuries before countries resembling any of those today — such as the Roman Empire — came into existence.