The first major European settlement was built in Arizona in 1752 at Tubac by the Spanish; it was a military outpost on the Santa Cruz River, north of Nogales. This settlement was a response to unrest among the Pima, one of several Indian tribes.
The Spanish in Arizona were explorers and missionaries as well as settlers. From 1539 to 1605, four Spanish expeditions crossed the territory in fruitless attempts to find treasure. Franciscans came from the Rio Grande to work among the Hopi Indians. Jesuits came from the south, led by Eusebio Kino in 1692, for mission work among the Pima and eventually established a mission station near Tucson. Evidence of a human presence in Arizona dates back more than 12,000 years.