In the southwestern United States, Pima County encompasses a mosaic of cultures and history. Living together in this region are Native American tribes with roots going back to prehistoric times, descendants of Spanish settlers who colonized the valley in the late 1600s, Mexican families who settled the area before the 1854 Gadsden Purchase, and current generations of late-19th-century American pioneers who ventured into the borderland of the Arizona Territory seeking new beginnings. Signs of a rich cultural heritage are everywhere. The Tohono O'odham and Yaqui peoples are a vital part of the community. Preserved missions, presidio fortresses, and ranches are evidence of the legacy of Spanish exploration, mission building, and colonization that began in the late 1600s. Streets in Tucson, lined with Sonoran-style adobe houses, recall when this region was part of Mexico. Ghost towns, old mines, military forts, and Territorial-era ranch houses are visible reminders of a series of gold and silver rushes, the settling of the West, and the rise of a cattle industry.