Looking at the chapter entitled "Reaching Out" in Traditions & Encounters by Bentley and Ziegler: What factors explain the increasing trade and interaction during these years and how did they relate to the role trade played in other societies?
The years referred to in this chapter are the years from 1000 to 1500 CE. According to the authors of this book, there was more trade and more interaction between different cultures because there was more long-distance travel. There were three reasons for this travel.
One of the reasons was trade. Trade became more possible because of technology and because of exploration. As Europeans came to find new routes to places like the Indian Ocean, more trade was possible. As technology like the magnetic compass and like better ships became available, it became easier for trade to happen over long distances. This led to more trade and to more interaction between cultures.
A second reason for travel was diplomacy. As there came to be more contacts between various cultures, there came to be more of a need for diplomatic contact as well. For example, Pope Innocent IV sent envoys to the Mongols in the 1240s. As another example, the Mongol ilkhan of Persia sent an emissary to the pope and to European political leaders in the 1280s.
Finally, there was travel for missionary purposes. Both Christians and Muslims tried to proselytize other cultures. They sent out missionaries along trade routes, hoping to convert people to their faiths.
Thus, we can see that there was more trade and more interaction during this time period because there was more long-distance travel.