Wikipedia 10K Redux by Reagle from Starling archive. Bugs abound!!!
Around 2000-1600 BC new groups started appearing around the peripheries of civilization. These are associated with bronze (copper+tin) implements, chariot archers, warrior nobilities, and generally speaking IndoEuropean languages. They probably fanned out from a homeland around the CaspianSea. Around the end of the period this process intensified, and most of the older civilizations were overrun. In the west, the first Greeks - the Achaeans - entered the country and founded the MycenaeanCivilization. This was partially derivative from the older MinoanCivilization on Crete, but soon came to dominate it. Further west, various groups - mostly notably the CelticPeoples - spread over Europe, almost entirely displacing the original cultures. In the east, various Iranian groups appeared. These include the nomadic Scythians, the Kassites who conquered Babylonia, the Mitanni who pushed the Hurrians into northern Mesopotamia, and the IndoAryans who destroyed the civilization of Harappa. At around the same time the semitic Hyskos overran Egypt, though they were ejected soon after. In these last few cases the IndoEuropean nobility were minorities ruling over a predominantly foreign people. Around this time, too, the first civilization in China - the ShangDynasty - appears. This probably was influenced by yet another group of IE migrants, the Tocharians, but not enough work has been done to confirm this hypothesis. Around 1200 BC most of the bronze age kingdoms collapsed and urban centers all across the eastern meditteranean were sacked by raiders, all within a few decades. The following few centuries were dark ages for Greece and the Near East. By the time civilization had recovered, iron tools had become common, and a new era had begun.