Located in what is now Guatemala and other parts of Central America, the Mayan empire stood out among ancient civilizations with its mastery of agriculture, pottery, art and writing.

They also were skilled in mathematics, using a number system that included zero, and time keeping, developing a complex 365-day calendar.

The first cities appeared in 750 BCE. During the 9th century, however, the Mayans appeared to have suffered a significant political collapse.

Many archaeologists say the decline was likely caused by a number of factors, including warfare, overpopulation and drought. In addition, the population suffered significantly from disease and war when the Spanish conquistadors arrived in force in the 16th century.

While the empire itself faded away, smaller units of its civilization continued to flourish, and millions of people of Mayan ancestry still populate the region today.