50 POINTS

In three paragraphs explain ways that the physical and natural environment put limits on the directions and locations of trade routes in premodern times?

Traversing as they do all of Eurasia, the Silk Roads encompassed almost every climate and vegetation zone and crossed every kind of terrain. This sketch of Silk Road geography has the modest aim of introducing a few of the important features of Eurasian physical geography which help us to understand patterns of human habitation and interaction across that vast expanse. There are always regional variations which deserve more detailed treatment. Before the advent of modern technology, geography and ecological zones were critical determinants of where and how people lived, moved and interacted. Boundaries such as we know them, delineated by modern states, did not exist, but boundaries there were, either natural or manmade, and in both cases they turn out to have been quite permeable.