The history of the San Fernando Valley from its exploration by the 1769 Portola expedition to the annexation of much of it by the City of Los Angeles in 1915 is a story of booms and busts, as cattle ranching, sheep ranching, large-scale wheat farming, and fruit orchards flourished and faded. Throughout its history, settlement in the San Fernando Valley (usually called simply "The Valley") was shaped by availability of reliable water supplies and by proximity to the major transportation routes through the surrounding mountains.

Native peoples and the coming of the Spaniards

Topography and early settlement Before the flood control measures of the 20th century, the location of human settlements in the San Fernando Valley was constrained by two forces: the necessity of avoiding winter floods and need for year-round water sources to sustain communities through the dry summer and fall months. In winter, torrential downpours over the western-draining watershed of the San Gabriel Mountains entered the northeast Valley through Big Tujunga Canyon, Little Tujunga Canyon, and Pacoima Canyon. These waters spread over the Valley floor in a series of braided washes that was seven miles wide as late as the 1890s, periodically cutting new channels and reusing old ones, before sinking into the gravelly subterranean reservoir below the eastern Valley and continuing their southward journey underground. Only when the waters encountered the rocky roots of the Santa Monica Mountains were they pushed to the surface where they fed a series of tule marshes, sloughs, and the sluggish stream that is now the Los Angeles River.

By the time the Spanish conquest of Mexico reached Alta California in 1769, successive groups of indigenous peoples, or Native Americans, had inhabited the area for at least 7,000 years. These peoples tended to settle on well-watered and wooded areas at the Valley's margins. The Tongva, who spoke the Tongva language, a Uto-Aztecan or Shoshonean language, had a series of villages in the southern Valley along or near the river, including Totongna (near modern-day Calabasas), Siutcanga (near Encino; means "place of the oak" in Fernandeño) and Kawengna (which the Spanish would write as Cahuenga; it means "place of the mountain"). In the north-central Valley was an apparently permanent village called Pasakngna (Fernandeño: Paséknga, of unclear etymology), in the lower foothills of the mountains near natural springs and a tule marsh. Other characteristic place-names of Tongva origin in the Valley include Tujunga (Fernandeño: tuxunga, which means "place of the old woman") and Topanga (in Tongva, , and in Fernandeño, Tupá’nga, with a root topaa’-/tupá’- that likely comes from Ventureño). The Tataviam were established in the valleys to the north; Pacoima (Fernandeño: pakoinga or pakɨynga) is believed to be of Tataviam-Fernandeño people's Tataviam language origin and means the entrance in the Fernandeño dialect.

The Hokan-speaking Chumash people inhabited Malibu, the Santa Monica Mountains, and the Simi Hills in the western area of the Valley, and much of the coastal areas to the northwest. At Bell Creek below the rocky outcropping called Escorpión Peak (Castle Peak), Chumash pictographs and other artifacts have been identified by archeologists at a site, Hu'wam, which is thought to have been a meeting place and trading center for the Tongva-Fernandeño and Chumash-Venturaño.SSPSHP ethnohistory In the Simi Hills the Burro Flats Painted Cave pictographs are located on Rocketdyne's Santa Susana Field Laboratory property, inaccessible but well protected. The Tataviam-Fernandeño people inhabited the foothills of the Santa Susana Mountains in the Valley (and north in the Santa Clara River area). The Tongva-Fernandeño inhabited the Valley, along the tributaries to the Los Angeles River.

Exploration In 1769, the expedition led by explorer Gaspar de Portolà reached the Los Angeles area of California overland from Baja California. Accompanying him were two Franciscan Padres, Junípero Serra and Juan Crespí, who recorded the expedition and identified locations for a proposed network of missions, along which the royal highway (El Camino Real) was eventually built.

After camping at and naming the location that would become the Pueblo de Los Angeles, the expedition proceeded westward before turning north through the Sepulveda Pass over the Santa Monica Mountains on the feast day of Saint Catherine of Bologna.

The watering place was a pool fed by a perennial spring at what is now Encino, near the village of Siutangna. The name El Valle de Santa Catalina de Bononia de los Encinos refers to the encinos or evergreen Coast Live Oaks that studded the area. The expedition proceeded northward, camping at a site in the northern Valley before crossing over the mountains into the Santa Clarita Valley.

Father Crespí had identified a location along the Los Angeles River that would be perfect for a settlement, possibly a mission, but in 1781, King Charles III of Spain ordered that a pueblo be built on the site, which would be the second town in Alta California after San José de Guadalupe, founded in 1777. By royal edict, all of the waters of the river and its tributaries were reserved for the Pueblo de Los Angeles, a condition which would have a profound impact on development of the Valley.

Mission San Fernando

By the end of the century, Spain had issued two grazing concessions north of the pueblo that included the southeastern corner of the Valley, Rancho San Rafael and Rancho Portesuelo. Francisco Reyes, alcalde or mayor of Los Angeles from 1793 to 1795, had set up a grazing operation which he called Rancho Encino located in what is now Mission Hills near the village of Pasakngna. Reyes's property had a substantial water supply from artesian wells and limestone for building, and was situated a day's walk from the existing missions San Gabriel and San Buenaventura. In or shortly before 1797 he was persuaded to cede this land to the Franciscans to be the site of a new mission, receiving in exchange a square league () of land in the southern valley by the perennial spring where the Portola Expedition had first entered the Valley. This property he also called Rancho Encino (also recorded as El Encino and Los Encinos).

Mission San Fernando Rey de España was founded at Reyes's original rancho site on September 8, 1797, by Father Fermín Lasuén. The mission's grazing lands extended over the flatlands of the valley, and it also claimed jurisdiction over several smaller valleys to the north and west. From this time, the valley began to be called after the mission.

The fathers were charged with "civilizing" the native peoples, which they named according to the mission which had jurisdiction over them. The native peoples associated with Mission San Fernando were called Fernandeños regardless of tribal affiliation or language, as those associated with Mission San Gabriel were called Gabrielinos. As the 19th century dawned, 541 Indians did the heavy work of the Mission San Fernando, tending the livestock and working the farmlands watered by irrigation from the mission's wells. The mission was famed for its red wine, and also grew pomegranates, figs and olives. By 1826, 56,000 longhorn cattle and 1,500 horses grazed on the mission lands of the valley floor.

Mexican rule Ranchos

In 1821, Mexico achieved its independence from Spain, and California came under control of the Mexican government. The 1824 Mexican Colony Law established rules for petitioning for land grants to individuals in California. Regulations enacted in 1828 attempted to break the monopoly of the missions and also made land grants easier to obtain. The procedure included a diseño - a hand drawn sketch map. The Mexican Governors of Alta California gained the power to grant state lands, and many of the earlier Spanish grazing concessions were subsequently patented under Mexican law.

Many Californios in the Los Angeles area wanted the mission's rich grazing lands to be made available to private citizens, while those in the north, including Mexican governor General Manuel Victoria, preferred to keep the mission system intact. Late in 1831, the Californios rose in armed rebellion against the governor, who led a party of soldiers to the Valley to put down the rebellion. The southern ranchers rode into the Valley via the Cahuenga Pass and the two armies faced off in a skirmish (Battle of Cahuenga Pass) that left one man dead on either side. Although the rebels retreated to the pueblo, they were victorious in defeat; the wounded governor resigned and returned to Mexico. Popular pressure increased on the government to disestablish the missions, and laws were passed to secularize the missions on August 17, 1833.

In 1843, Don Vicente de la Osa (or del la Ossa) was granted one league of land along the Los Angeles River at the southeast corner of the Valley which he named Rancho Providencia. Brief History of Vicente de la Ossa and Family The nearby Battle of Providencia of February 20, 1845, was another face-off between Californios and an unpopular Mexican governor, Manuel Micheltorena, who proposed to return the mission lands to the control of the church. The only reported fatalities in the day-long cannon battle along the river were two horses and a mule, but Governor Micheltorena was captured and summarily shipped back to Mexico. He was replaced by Pío Pico, a native Californio, who would become the last Mexican governor of California.

Mexican–American War

California was "land rich but poor in every other way, lacking cash, gunpowder, and support from Mexico." Governor Pico prepared for the inevitable war with the United States, and in 1845 began dispersing the vast mission lands. A square of land at the west end of the Valley near the historic Chumash village Hu'wam was granted to three of the mission Indians under the name Rancho El Escorpión. The majority of the mission's grazing lands and mission buildings were leased to the governor's brother Andrés Pico. After the United States declared war on Mexico on May 13, 1846, Pico sold the mission property outright to Eulogio de Celis for much-needed cash; Celis graciously extended the terms of his friend Andrés Pico's lease. From this time the property was known as Rancho Ex-Mission San Fernando.

United States troops quickly took control of the presidios at Monterey and San Francisco and proclaimed the Conquest complete. In Southern California, the Mexicans, for a time, resisted American troops, but when defeat became inevitable, Pío Pico fled to Mexico. Don Andrés Pico arranged the peaceful surrender of Los Angeles to American forces under Lieutenant-Colonel John C. Frémont. The Treaty of Cahuenga ending the hostilities in California was signed at an adobe owned by the Verdugo Family at Campo de Cahuenga near the mouth of the Cahuenga Pass, at the southeast corner of the Valley, on January 13, 1847.

The Treaty of Guadalupe Hidalgo in 1848, ended the war and ceded California to the United States.

Gold Rush and statehood Cattle boom In Northern California the California Gold Rush starting in 1849 created an influx of over a hundred thousand prospectors and a heavy demand for beef from southern California. Herds of cattle were driven to northern markets serving the gold fields. In the southern Valley, de la Osa sold Rancho La Providencia to David W. Alexander and acquired the Rancho Encino, successfully raising cattle on the property. De la Osa took formal title to the Rancho under California law in 1851.