Every later chapter of Scottsdale history rests on this one. From roughly 450 to 1450 CE, the Hohokam built the largest irrigation network in the ancient Americas north of Peru across the Salt River Valley — canals so well graded that nineteenth-century settlers simply cleaned them out and used them again. Their fields grew corn, beans, squash, agave, and cotton; their villages traded shell, obsidian, and macaws across half a continent.
Around 1450 the Hohokam disappear from the archaeological record, but their descendants never left. The Akimel O’odham (Pima) and Piipaash (Maricopa) peoples farmed on along the rivers, and in 1879 the federal government established the Salt River Reservation — today’s Salt River Pima-Maricopa Indian Community — along what would become Scottsdale’s entire eastern boundary, nine years before Winfield Scott arrived.
The American approach came in stages: Fort McDowell (1865) put an Army post and its supply trails northeast of the future townsite; Jack Swilling’s crews re-dug the ancient canals near Phoenix (1867); and the Arizona Canal (1883–85) finally carried water across the empty benchland where a chaplain would soon stake 640 acres — the story that opens the Founding & Pioneer era.
This era chapter is a framework page — the full deep-dive (Hohokam engineering, the platform mounds and ballcourts near the Indian Bend Wash, O’odham oral history, and the archaeology beneath modern Scottsdale) lands in a later pass.