the location of the earliest civilization or complex society, meaning that it contained cities, full-time division of labor, social concentration of wealth into capital, unequal distribution of wealth, ruling classes, community ties based on residency rather than kinship, long distance trade, monumental architecture, standardized forms of art and culture, writing, and mathematics and science. It was the world's first literate civilization, and formed the first sets of written laws. Bronze metallurgy spread within Afro-Eurasia from c. 3000 BCE, leading to a military revolution in the use of bronze weaponry, which facilitated the rise of states. Classical antiquity Although state-forms existed before the rise of the Ancient Greek empire, the Greeks were the first people known to have explicitly formulated a political philosophy of the state, and to have rationally analyzed political institutions. Prior to this, states were described and justified in terms of religious myths. Several important political innovations of classical antiquity came from the Greek city-states and the Roman Republic. The Greek city-states before the 4th century granted citizenship rights to their free population, and in Athens these rights were combined with a directly democratic form of government that was to have a long afterlife in political thought and history. Feudal state During Medieval times in Europe, the state was organized on the principle of feudalism, and the relationship between lord and vassal became central to social organization. Feudalism led to the development of greater social hierarchies. The formalization of the struggles over taxation between the monarch and other elements of society (especially the nobility and the cities) gave rise to what is now called the Standestaat, or the state of Estates, characterized by parliaments in which key social groups negotiated with the king about legal and economic matters. These estates of the realm sometimes evolved in the direction of fully-fledged parliaments, but sometimes lost out in their struggles with the monarch, leading to greater centralization of lawmaking and military power in his hands. Beginning in the 15th century, this centralizing process gives rise to the absolutist state. Modern state Cultural and national homogenization figured prominently in the rise of the modern state system. Since the absolutist period, states have largely been organized on a national basis. The concept of a national state, however, is not synonymous with nation state. Even in the most ethnically homogeneous societies there is not always a complete correspondence between state and nation, hence