Rancho Yokaya (also called "Llokaya") was a 35,541-acre (143.83 km2) Mexican land grant in present day Mendocino County, California given in 1845 by Governor Pío Pico to Cayetano Juárez. The name Yokaya means "south valley" in the language of the Pomo people. The grant extended along the Russian River from the southern end of Ukiah Valley to the northern end of Redwood Valley, from one to two miles wide, and approximating sixteen miles in length, and encompassed present day Ukiah.
Neither Spanish nor Mexican influence extended into Mendocino County beyond establishing in southern Mendocino County: Rancho Sanel at Hopland in 1844 and Rancho Yokoya in 1845.
Cayetano Juárez (1809 - 1883) was a soldier at Presidio of San Francisco until 1836. Juárez married María de Jesús Higuera (b. 1815), daughter of Francisco Higuera in 1835. In 1836 Juárez was made mayordomo at Sonoma. For his decade of service to the Mexican government, Juárez was granted Rancho Tulucay in present day Napa County, California in 1840. In 1844 he was elected Alcalde of Sonoma. Although often away, Juárez resided on Rancho Tulucay until his death in 1883, and is buried in the Tulocay Cemetery in Napa, California. Juárez was granted the eight square league Rancho Yokaya in 1845.
With the cession of California to the United States following the Mexican-American War, the 1848 Treaty of Guadalupe Hidalgo provided that the land grants would be honored. As required by the Land Act of 1851, a claim for Rancho Yokaya was filed with the Public Land Commission in 1852, but rejected by the Commission in 1854. But on appeal was confirmed by the District Court in 1863, and US Supreme Court in 1864, and the grant was patented to Cayetano Juárez in 1867.