The fertile land at the base of Sentinel Peak was used for agriculture from circa 2000 BCE until the 1930s. Bedrock mortars found on the sides of the peak are believed to have been used to grind corn and mesquite beans into flour. In the 1690s, the O'odham people living in the area were visited by Father Eusebio Francisco Kino, who established the nearby Mission San Xavier del Bac. After Presidio San Augustin del Tucson was constructed in 1775, sentinels were stationed on the peak to watch for raiding Apaches.