Ancient farmers in southwestern Colorado were far more numerous than their Mesa Verde neighbors, and by the twelfth century perhaps 12,000 people lived in the green canyons and plateaus of the Montezuma Valley, raising beans, squash, and corn, living first in underground structures and later in masonry pueblos, and crafting fine stone tools, elegant pottery, and intricate baskets. Around A.D. 1300, for reasons that may have included a long drought, hostile neighbors, or depleted natural resources, they left their villages, and archaeologists believe many migrated south, establishing new settlements or joining existing ones that gave rise to modern-day Pueblo culture. The term Four Corners dates to 1868, when new territorial demarcations created America’s only quad-state conjunction, but long before that the region was a meeting ground of peoples, including in the seventeenth century the Spanish, the Utes, the Navajos, and the Apaches, whose descendants still live there today. With its climate and rugged terrain, the region retained an air of remoteness, and as recently as the 1870s parts of it had never been seen by non-Indians. Mining, tourism, and agriculture all shaped the area during the twentieth century, yet it remains known for both striking beauty and deep cultural history.