As I read about the postclassical or third-wave civilization era, I couldn't help but compare the impactof  this era on human development with the impact that the neolithic era had on human development. The neolithic era involved the spread of agriculture while the postclassical era
involved the rapid spread of commerce.
     Both eras lead to the stratification of societies. Those who could store more crops and food reached
a higher status.  During the third-wave civilization era, those who could import fine products such as silk and gold, reached a higher status. Likewise, both eras lead to the spread of disease, though during the neolithic era many of the diseases came from housing animals in close proximity with humans while
during the postclassical era, disease was spread from human to human. Another similarity is that both North and South America were impacted by these two eras at a much slower rate than the rest of the world. This was due, in part, to the movement between the northern and southern hemispheres, which had very different weather  conditions. Civilizations in the Americas were blocked from each other by geographical barriers such as rain forests. They also lacked beasts of burden such as horses or camels
to carry materials from one place to another.
     Another very interesting aspect of the postclassical era involved the spread of religions. I was not aware that Islam spread to Africa while Buddhism spread to Asia through trade during this particular time. Buddhism spread via the Silk Road while Islam spread through trade on the Indian Ocean.

I have attached an article about early Roman shipping. Archeologists have discovered evidence that
early Romans went further out to sea then first thought. They didn't just hug the coastline.



http://www.huffingtonpost.com/2012/05/29/ancient-roman-shipwrecks-greece_n_1552492.html