Within that expanse, the Maya lived in three separate sub-areas with distinct environmental and cultural differences: the northern Maya lowlands on the Yucatan Peninsula; the southern lowlands in the Peten district of northern Guatemala and adjacent portions of Mexico, Belize and western Honduras; and the southern Maya highlands, in the mountainous region of southern Guatemala. Most famously, the Maya of the southern lowland region reached their peak during the Classic Period of Maya civilization (A.D. 250 to 900), and built the great stone cities and monuments that have fascinated explorers and scholars of the region.