I think one major change is the types of goods traded on the silk road. In the very beginning of the open of the silk road, people traded silk, porcelain and teas, but later as the technology advanced, especially the Industrial Revolution brought many new technologies and machines on the silk road.

The industrial revolution didn't occur until the 18th and 19th centuries. The silk road changed from trading predominantly luxury items such as silk, spices and porcelain, to becoming more of a route for staple (necessary) goods such as clothes, food, and livestock.