¶ … expansive period, important force change development evolution world civilizations preclassical era middle ages ? agricultural developments, technology, industrial development . From approximately 3500 BCE to 1500 CE, in this expansive period, what has been the most important force of change in the development and evolution of world civilizations from the pre-classical era through the middle ages and why?

The most important force of change during the vast span of years from 3500 BCE to 1500 CE was the development of the modern, bureaucratic state. Only with an effectively-organized government could a nation martial a fighting force to defend its borders, protecting the intellectual and artistic treasures of its civilization from ruin. And only with an effectively-organized state government could empires have been built. The building of empires, and the trade and cultural exchanges they fostered, created what today we would call the modern world. In the absence of effectively-organized state governments, Europe dissolved into a patchwork of tribes and feudal territories. It took centuries to reconstruct the learning that had been lost as the result of the ebbing away of a central governing authority.

Ancient Greece is often called the cradle of modern civilization. Greece was the first civilization to generate what could be called a modern democracy, in ancient Athens. The ancient Greek philosophers created the beginnings of a tradition of 'rational' inquiry, where seemingly self-evident truths about the universe were questioned. Their ideas such as the Pythagorean Theorem, geometry, and the Socratic Method are still used today. Greece was not really a nation at this time, but rather a...

The terrain of Greece provided some protection from the outside world, although the Greeks were eventually conquered by the Romans. The major Greek city-states had their own empires, as well as traded with the outside world. This enabled them to engage in cultural dialogue with other peoples, yet also retain a certain degree of cultural integrity within each city-state. Even the famously militaristic city-state of Sparta had a highly evolved military culture and an organized city state.
The successors to the Greeks, the Romans did not develop as complex intellectual and religious life like the Greeks. However, the Roman state was even more formally organized than that of the Greek state. The foundations of Roman life were centered upon a Roman male's civic obligations to the state. The Emperors were even deified. The Roman conquest led to a temporary peace, when Rome ruled for over two centuries. Most of Rome's greatest innovations during the early years of Imperial rule involve setting down infrastructure -- an infrastructure of laws and roads, for example, which still stand to this day. All regions within the Empire were supposed to obey Rome, and there was a continual trafficking of people, goods, services, and ideas between the central leadership and all corners of the Empire. Rome created a truly cosmopolitan community amongst its subjects.

However, the 'Pax Romana' came at a great price -- Rome, to an even greater degree than Greece, required slavery to function, and there was a chasm between the rich and the poor. Wealthy patrons would provide charity, and the state attempted to keep…