Because they were so close to these rivers, they serve as sources of drinking water. What gave opportunity for people to settle and become sedentary, focusing initially on agriculture and land security, with this the population grew and avoided the risks of nomadic communities, not having to go to places unknown or dangerous or run out of food. Therefore, over time they then focused on more complex areas such as politics, economy and architecture. Promoting the development of the community that over the years were the foundations of modern civilization.
guys I promise you its sewing machine because the sewing machine sewed the clothes while thy cotton gin only worked on the cotton not actual clothes. so the answer should be SEWING MACHINE.
