It is said that Thales, considered the first philosopher, was in the import-export business, invented the concept of the mathematical proof in order not to be short-changed in overseas transactions, and began thinking up naturalistic explanations for such phenomena as eclipses and fossils.
Greek culture evolved a system of independent city states that were usually at war with one another, and despite Athenian culture and political dominance, Athens was overthrown by the conservative and militaristic Spartans, and never regained its former dominance. Greece and much of the rest of the known world was first unified under the short-lived empire created by Alexander of Macedon, but then fell apart into six different provinces ruled by his generals. The Mediterranean world was not permanently unified until it was all conquered by the Romans.
The pattern in India was roughly similar. The earlier, autonomous Indus valley civilization apparently was conquered about 1500 by the Indo-European "Aryan" invaders, who were part of the general expansion of the Indo-European-speaking people going on at that time. This conquest created a class structure that survived into modern times, with the mainly Aryan Brahmin priestly class and Kshatriya warrior class being highest in social rank, and the essentially Dravidian, darker-skinned native peoples forming the lowest classes. The Indus valley was pulled into the Persian Empire as the satrapy of Hindush. After Alexander's conquest of the Persian Empire shattered the old system, Chandragupta unified India into its first overall kingdom.
In China, events were much less influenced by outside invasions. The Shang Dynasty seems to have been created by native peoples, and provided a loose confederation of larg