I believe the answer is:
They establish a means of obtaining new goods through the region.
Through the trade route, many civilizations could trade various commodities that might not exist in their civilization, such as crops, spices, threads, porcelain,arts, etc.
Trade routes brought a cultural exchange that resulted in significant advancements in civilization throughout the region.
Through these trading, many people from different civilizations are made to interract and communicate with one another. During this process, cultural exchange happen between different civilizations and integrated with one another.