Mostly they affected it through their imperialism. They would colonize and take over countries for resources, and with them they would bring their technologies and things that they needed. After they left these things stayed, things like telephone and telegram lines and similar things. Culturally, they would mostly disregard the local culture and impose their own which would often be accepted and kept by the locals, but often there was also warfare.
Answer: 15 kilometers per mile
Explanation: Duh
Civilizations developed around rivers because their waters provided places to hunt and fish.
Also, as the rivers flooded, the lands around them became fertile. This allowed them to support farming.
In addition, because they provided a steady supply of drinking water.
Moreover, goods and people could be transported easily
Finally, River valleys not only have water, they also often have a broad, flat floodplain that is readily adapted to agriculture.
