The Tongva lived in what is now Pomona and the Los Angeles Basin when the Spanish arrived. Under Mexican rule, Ricardo Vejar and Ygnacio Palomares claimed the land in the 1830s, and the first Anglo-Americans came before California became part of the United States in 1848.
More about Pomona
In 1866 the landowner Phillips sold a parcel to William "Uncle Billy" Rubottom, who founded a town there and named it Spadra after his hometown in Arkansas. Three miles west of the later Pomona station, Spadra became a stagecoach stop, with Rubottom's hotel and tavern, and by 1870 it had 400 to 500 residents, three stores, a school and a post office. Phillips persuaded the Southern Pacific to build to Spadra in 1873 and built his Phillips Mansion there in 1875, but when the railroad was extended east to Colton, Spadra faded. The mansion and the Spadra Cemetery are all that remain, and Pomona annexed the area in 1964.
In 1875 the Los Angeles Immigration and Land Cooperative Association held a contest to name the new town. The winner, submitted by the citrus worker Solomon Gates, was Pomona, the Roman goddess of fruit. Water and railroad access made Pomona the western anchor of the citrus belt in the 1880s, and the city was incorporated on January 6, 1888. In the 1920s it was known as the Queen of the Citrus Belt.
Sources
Wikipedia: Pomona, California