What were the major causes of the age of exploration?

Trade, obtaining wealth, and territorial expansion.

Explanation:

The age of exploration started in the 15th century. The main reason for this was the Ottoman Empire which stood on the way of trade between Europe and Asia, was very restrictive and demanded high taxes. The Europeans didn't fancied this and they started to look for other ways to Asia, which led to discovering sea routes that were safe, but also discovering new lands.

Once the new lands were discovered the interest in exploration skyrocketed. Every country wanted to become rich and get as much wealth as possible, and there were some promising signs that the new lands have much to offer. That also led to aspirations for territorial expansion and controlling as much land as possible, most because of economic goals.

by 1880, germany had more rail lines than great britain and russia.