History and Map
The first European to see it was Gabriel Moraga in 1806. It was later named Rio Estanislao in honor of Estanislao, a mission-educated renegade Native American chief who led a band of Native Americans in a series of battles against Mexican troops until finally being defeated by General Mariano Vallejo in 1826.
Between 1843 and 1846, when California was a province of independent Mexico, five Mexican land grants were granted in Stanislaus County.
Stanislaus County was formed from part of Tuolumne County in 1854.