Spain was a key leader in Europe because of their global explorations and rediscoveries of the New World. After they discovered the New World their culture in trade expanded vastly. Because they were conquering quickly and effectively Spain gained in control and in riches. These places were rich in gold and silver allowing Spain to grow it's power in the New World. Ferdinand and Isabella were ruling Spain. With the expansion in the New World, gained control of a lot of land a this caused them to expand their empire vastly.