[msla]

> I can’t tell what is there that make a region a key factor in determining light or dark ages of physical sciences.

My point is that regions have dark ages, if dark ages exist at all, and trying to disprove the existence of a regional dark age by pointing out that other regions weren't in a dark age is a non sequitur. For example, I think it's widely recognized that the Islamic Golden Age occurred during at least part of the time usually regarded as Western Europe's Dark Age.

[smga]

The historical relation between the descent of Rome into the Western dark ages, the subsequent rise of the non-Western Islamic world, and the rise again of High Medieval Western Europe is something I learned only in recent years. [0]

The fall of Rome in Western Europe was followed, after a lag of some centuries, by the rise of Islamic civilization and its peak in the Islamic Golden Age (c. the Umayyad and early Abbasid Caliphates). During this golden age, the Islamic world became a center of trade routes, agriculture, population, wealth, and knowledge-- a center of civilization.

But the later Abbasid Caliphate declined as well, marked by the dispersal of trade routes, agriculture, population, wealth, and knowledge. Then, some of that knowledge, wealth, and control of trade routes migrated West during its High Middle Ages, bootstrapping the Western millennium. The rest, is History.

[0] Bas van Bavel, _The Invisible Hand_