A region advances in scientific knowledge by trade because another region’s sceintific knowledge may be greater than their’s. Trading will allow that knowledge to be passed along to the reciever in the form of goods. By examining those goods, people can find out how they work and learn to replicate those items themselves. The beneficiary may also see ways to improve the item that the original creator did not.

Is this for World History? If so, I would say that trade helps a region’s scientific advancement because it spreads ideas across different areas, which have the chance to improve upon them. For instance, if one society came up with metal-working, trade between that region and another would convey that invention to other regions. These regions could improve upon the original idea and come up with an even better invention.

In the middle ages, it was typical for a person to spend most of their lives within a day’s walk from home. Merchants, and people traveling on business were an exception to this rule. Devices sold in one place could be analyzed and duplicated, as your other respondent said. Larger mechanical devices, such as the use of water wheels for mills could be either sketched, or possibly replicated from memory. The crusades were a jump start for this kind of thing, with pilgrims finding such things like the Damascus Hospital that focused on diet, and isolated those with contagious diseases. Of course, pilgrims are going to the Holy sites for spiritual reasons, but there was usually time for business as well. The Lateen sail, was a major innovation taken from the mid east, making it possible to “tack” with a vessel against the wind. Gun powder, from eastern sia, came into Europe through west Asia. The central rudder also came to Europe through the mid east. These last three played a major part in the age of Exploration of the 15th to 17th centuries.