[2] However, sources also show that Acjachemen people shared sites with other Indigenous nations as far north as Puvunga in contemporary Long Beach.

Spanish colonists called the Acjachemen Juaneños, following their conversion to Christianity at Mission San Juan Capistrano in the late 18th century.

Each clan had its own resource territory and was politically independent; ties to other villages were maintained through economic, religious, and social networks in the immediate region.

[11] A set of highly important Acjachemen villages (Acjachema, Suvit, and Putuidem) were concentrated along the lower San Juan Creek.

The majority of early converts were often children, who may have been brought by their parents in an attempt to "make alliances with missionaries, who not only possessed new knowledge and goods but also presented the threat of force."

"[13] While, before 1783, those who had been converted, known as "Juaneños, both children and adults, represented a relatively small percentage of the Acjachemen population, all that changed between 1790 and 1812, when the vast majority of remaining non-converts were baptized.

[4] The Acjachemen resisted assimilation by practicing their cultural and religious ceremonies, performing sacred dances and healing rituals both in villages and within the mission compound.

Missionaries attempted to prevent "Indigenous forms of knowledge, authority, and power" from passing on to younger generations by placing recently baptized Indian children in monjerios "away from their parents from the age of seven or so until their marriage."

Following the Mexican secularization act of 1833, "neophyte alcades requested that the community be granted the land surrounding the mission, which the Acjachemen had irrigated and were now using to support themselves."

Terrestrial and marine fauna refuse, food storage vessels, specialized craft goods, ritual artifacts culturally associated with elite clan lineages, and interregional trade connections were found at the Puhú village site.

[11] However, while Acjachemen "claimed and were granted villages," there was "rarely" any legal title issued, meaning that the land was "never formally ceded" to them following emancipation, which they protested as others encroached upon their traditional territory.

Although the Acjachemen were now "free," they were "increasingly vulnerable to being forced to work on public projects" if it was determined that they had "'reverted' to a state of dependence on wild fruits or neglected planting crops and herding" or otherwise failed to continue practicing Spanish-imposed methods of animal husbandry and horticulture.

[17] Because of a lack of formal recognition, "most of the former Acagchemem territory was incorporated into Californio ranchos by 1841, when San Juan Mission was formed into a pueblo.

The formation of the San Juan pueblo granted Californios and Acjachemen families solars, or lots for houses, and suertes, or plots of land in which to plant crops.

"[22] American occupation resulted in increasing power and wealth for European immigrants and Anglo-Americans to own land and property by the 1860s, "in sharp contrast to the pattern among Californios, Mexicans, and Indians."

However, until 1920, for education beyond sixth grade, "students had to relocate to Santa Ana – an impossibility for the vast majority of Californio and Acjachemen families.

"[24] Gerónimo Boscana, a Franciscan scholar who was stationed at San Juan Capistrano for more than a decade beginning in 1812, compiled the first, comprehensive study of Acjachemen religious practices.

The Playanos held that an all-powerful and unseen being called "Nocuma" brought about the earth and the sea, together with all of the trees, plants, and animals of sky, land, and water contained therein.

These states of being were "altogether explicable and indefinite" (like brother and sister), and it was the fruits of the union of these two entities that created "...the rocks and sands of the earth; then trees, shrubbery, herbs and grass; then animals...".

[40] In 2008, the Acjachemen community successfully prevented the construction of a toll road highway that would have desecrated and irreparably harmed Panhe, a sacred ancestral town site.

[44] In 2021, Adelia Sandoval, Jerry Nieblas, and other Acjachemen members celebrated the opening of Putuidem Village, a 1.5-acre park (0.61 ha) in San Juan Capistrano, part of their original lands, which commemorates their history.