Bronze Age : The Bronze Age is the second part of the three-age system (Stone Age, Bronze Age, and Iron Age) for classifying and studying prehistoric societies, particularly the ancient societies of the Mediterranean and Near East. More broadly, the Bronze Age of any culture is the period during which the most advanced metalworking (at least in systematic and widespread use) in that culture uses bronze. This could either be based on the local smelting of copper and tin from ores, or trading for bronze from production areas elsewhere. Copper/tin ores are rare, as reflected in the fact that there were no tin bronzes in western Asia before 3000 BC. Many, though not all, Bronze Age cultures flourished in prehistory. Some cultures developed extensive written records during their Bronze Ages. In some areas of the world the Bronze Age followed the Neolithic age. However, in many parts of sub-SaharanAfrica, the Neolithic age was directly followed by the Iron Age. In some parts of the world, a Copper Age followed the Neolithic Age and preceded the Bronze Age. The place and time of the invention of bronze are controversial. It is possible that bronzing was invented independently in the Maikop culture in the North Caucasus as far back as the mid 4th millennium BC, which would make them the makers of the oldest known bronze; but others date the same Maikop artifacts to the mid 3rd millennium BCE. However, the Maikop culture only had arsenic bronze, which is a naturally occurring alloy. Tin bronze, which developed later, requires more sophisticated production techniques; tin has to be mined (mainly as the tin ore cassiterite) and smelted separately, then added to molten copper to make the bronze alloy. In Mesopotamia, the Bronze Age begins at about 2900 BCE in the late Uruk period, spanning the Early Dynastic period of Sumer, the Akkadian Empire, the Old Babylonian and Old Assyrian periods and the period ofKassite hegemony. In Ancient Egypt, the Bronze Age begins in the Protodynastic period, c. 3150 BCE. The Aegean Bronze Age begins around 3000 BC, when civilizations first established a far-ranging trade network. This network imported tin and charcoal to Cyprus, where copper was mined and alloyed with the tin to produce bronze. Bronze objects were then exported far and wide, and supported the trade. Knowledge of navigation was well developed at this time, and reached a peak of skill not exceeded (except perhaps by Polynesian sailors) until 1730 CE when the invention of the chronometer enabled the precise determination of longitude. The Minoan civilization based in Knossos appears to have coordinated and defended its Bronze Age trade. The late Bronze Age Urnfield culture, (1300–700 BCE) is characterized by cremation burials. It includes the Lusatian culture in eastern Germany and Poland (1300–500 BCE) that continues into the Iron Age. The Central European Bronze Age is followed by the Iron Age Hallstatt culture (700–450 BCE).