The Spanish Empire consisted of territories across Europe, the Americas, Africa, Asia and Oceania from the 15th through 20th centuries. In the 16th century, Spain took control of large parts of North and South America by conquering the Aztec and Inca empires through military tactics, alliances with rival groups, and the spread of disease. Though Spain's empire was vast, it declined in the following centuries through independence movements and military defeats against other European powers like France.