Before the arrival of European settlers, the secluded valley below the San Rafael Hills that is roughly congruent to Eagle Rock's present boundaries was inhabited by the Tongva people, whose staple food was the acorns from the valley's many oak trees. These aboriginal inhabitants were displaced by Spanish settlers in the late 18th century, with the area incorporated into the Rancho San Rafael. Following court battles, the area known as Rancho San Rafael was divided into 31 parcels in 1870. Benjamin Dreyfus was awarded what is now called Eagle Rock. In the 1880s Eagle Rock existed as a farming community.