For thousands of years the major civilizations of the world thrived in isolation from one another. These civilizations had very little contact with one another, and in many cases had no knowledge of each other.
This all began to change during the Dark Ages. Both Western Europe and China began to send out explorers in an effort to learn about the world around them. These explorers helped to expand the knowledge of their people.
As a result of their explorations, trade routes opened up between civilizations. Each nation specialized in certain types of products and goods. These goods would be shipped to far away nations in exchange for the goods that they specialized in.
Imagination is more important than knowledge.
The George Washington Bridge, linking New York to New Jersey, opened on October 24, 1931.