[michaelscott]

I have a pet theory about this and the development of "advanced" civilization in general, that civilizations always advance relatively rapidly due to constant conflict. It doesn't necessarily have to be military conflict, but it generally seems to have been right up to the 20th century.

Because Europe is geographically small, the probability of neighbour conflict is always very high especially when that small space contains such a high degree of variation in language and culture. If you add a particularly ambitious, capable and politically-placed individual to that mix like an Alexander the Great you tend to get empires forming.

I don't think this is specific to Europe at all; Asia has experienced similar rapid development throughout its history, many times being very technologically advanced from a global perspective, and the origin of smaller empires like the Aztecs, Iroquois and the Oyo in other parts of the world.