What are some of the ways that the physical and natural environment put limits on the directions and locations of trade routes in premodern times? 150 words at least pls

some ways the physical and natural environment put limits on the the directions and locations of trade routes is that designers and architects had to try to make their routes travel-friendly, and strong to withstand by travellers. certain trade routes came in between major countries in premodern times, for example: the silk road. the physical and natural environments of an area should be easy to travel through, which is why trade routes are usually on the most peaceful areas, such as a few desert, or a grassland, or a small forest. trade routes like the Amber Route follow this. most trade routes are small, and of no purpose whatsoever, some connecting 2 kingdoms, yet are still recognized as 'Trade Routes'. as for directions, trade routes will always go towards the area where certain substances are in scarcity, a barter trade. again, we use the silk road as an example, as silk is only made in china, yet it is sent to areas where silk is impossible to harvest, due to natural conditions. so directions are vital for trade routes. now, in this modern day-and-age, trade routes are not required. but there are still areas where certain substances cannot be manufactured, but we have imports. however in premodern times, trade of certain items were sent to areas of scarcity. our ancestors were not stupid, and they knew what they had to do for a certain resource. so, in a nutshell, this is how physical and natural limits influenced directions and licaqtions of premodern trade routes  

in all honesty, it really hasn't. except that hitler killed himself.