[12] Since the 2000s, historians have characterized the period immediately following the conquest of California as one in which U.S. miners, farmers, and ranchers on the American frontier engaged in the systematic genocide of indigenous Californians.

[13] In a 2019 executive order, Newsom announced the formation of a "Truth and Healing Council" to better understand the genocide and inform future generations of what occurred.

[17] For example, traditional use of fire by Californian and Pacific Northwest tribes, allowed them to "cultivate plants and fungi" that "adapted to regular burning.

The list runs from fiber sources, such as bear-grass and willow, to foodstuffs, such as berries, mushrooms, and acorns from oak trees that once made up sprawling orchards".

[17] Many practices were used to manage the land without tremendous destruction in other ways including "tillage, pruning, seed broadcasting, transplanting, weeding, irrigation, and fertilizing".

[20] The Native people of California, according to sociologist Kari Norgaard, were "hunting and fishing for their food, weaving baskets using traditional techniques" and "carrying out important ceremonies to keep the world intact".

[21] It was also recorded that the Indigenous people in California and across the continent had, and continue to, use "fire to enhance specific plant species, optimize hunting conditions, maintain open travel routes, and generally support the flourishing of the species upon which they depend, according to scholars[22] like the United States Forest Service ecologist and Karuk descendent Frank Lake".

Catholic Spanish missionaries, led by Franciscan administrator Junípero Serra and military forces under the command of Gaspar de Portolá, did not reach this area until 1769.

The mission was intended to spread the Catholic faith among the region's Native peoples and establish and expand the reach of the Spanish Empire.

[20] According to Castillo, the Native American population were forced to abandon their "sustainable and complex civilization" as well as "their beliefs, their faith, and their way of life".

[20] However, artifacts found at an archaeological site on San Clemente Island suggested that a group of Indigenous people were practicing traditional ways after the arrival of Europeans and Americans in other parts of California, and until potentially the 1850s.

He systematically described the fraud, corruption, land theft, slavery, rape, and massacre perpetrated on a substantial portion of the aboriginal population.

[65] The Amah Mutsun are a group of Indigenous peoples who were reported to be unable to pass on their traditions during this time, their practices remained untold for a number of years.

U.S. Army soldiers deployed to the valley stopped further killings and in 1862 the California legislature revoked a law which permitted the kidnapping and enslavement of Native Americans in the state.

Ishi had spent most of his life hiding with his tribe members in the Sierra wilderness, emerging at the age of about 49, after the deaths of his mother and remaining relatives.

During the 1850s, white people in the United States depended on individuals of Native American descent to cultivate vast areas of land in return for minimal or non-existent monetary compensation.

[26] According to M. Kat Anderson, an ecologist and lecturer at University of California, Davis, and Jon Keeley, a fire ecologist and research scientist with the U.S. Geological Survey, after decades of being disconnected from the land and their culture, due to Spanish and U.S. settler violence, Native peoples are slowly starting to be able to practice traditions that enhance the environment around them, by directly taking care of the land.

Anderson and Keeley write, "The outcomes that Indigenous people were aiming for when burning chaparral, such as increased water flow, enhanced wildlife habitat, and the maintenance of many kinds of flowering plants and animals, are congruent and dovetail with the values that public land agencies, non-profit organizations, and private landowners wish to preserve and enhance through wildland management".

Native American scholar Gerald Vizenor has argued in the early 21st century for universities to be authorized to assemble tribunals to investigate these events.

He says: Genocide tribunals would provide venues of judicial reason and equity that reveal continental ethnic cleansing, mass murder, torture, and religious persecution, past and present, and would justly expose, in the context of legal competition for evidence, the inciters, falsifiers, and deniers of genocide and state crimes against Native American Indians.

Genocide tribunals would surely enhance the moot court programs in law schools and provide more serious consideration of human rights and international criminal cases by substantive testimony, motivated historical depositions, documentary evidence, contentious narratives, and ethical accountability.

[139]Vizenor believes that, in accordance with international law, the universities of South Dakota, Minnesota, and California Berkeley ought to establish tribunals to hear evidence and adjudicate crimes against humanity alleged to have taken place in their individual states.

[141] In a speech before representatives of Native American peoples in June, 2019, California governor Gavin Newsom apologized for the genocide.

California Native American peoples suffered violence, discrimination and exploitation sanctioned by state government throughout its history ....

We can never undo the wrongs inflicted on the peoples who have lived on this land that we now call California since time immemorial, but we can work together to build bridges, tell the truth about our past and begin to heal deep wounds.

"[13][142] After hearing testimony, a Truth and Healing Council will clarify the historical record on the relationship between the state and California Native Americans.

[55] Historian Brendan C. Lindsay, argued that "rather than a government orchestrating a population to bring about the genocide of a group, [in California] the population orchestrated a government to destroy a group",[151] while William T. Hagen wrote that "[genocide] is a term of awful significance, but one which has application to the story of California's Native Americans".

For example, historian Richard White, in a review of Madley's An American Genocide, argues that "no reader of his book can seriously contend that what happened in California doesn't meet the current definition of "genocide"," citing the "relentless attacks by federal troops, state militia, vigilantes, and mercenaries [that] made the enslavement of Indians possible and starvation and disease inevitable".

[155] Writing about the experience of indigenous Californian women during this period, Women's studies scholar Gail Ukockis argues that "government officials were quite explicit about their genocidal intent,"[156] citing the 1851 State of the State address given by the 1st Governor of California, Peter Burnett, in which he said: "That a war of extermination will continue to be waged between the races until the Indian race becomes extinct must be expected.

[64] Responding to critics of the "genocide" charge that have argued that epidemics were the primary cause of Native mortality,[158] Ostler writes that "depopulation from disease more often resulted from conditions created by colonialism—in California, loss of land, destruction of resources and food stores, lack of clean water, captive taking, sexual violence, and massacre—that encouraged the spread of pathogens and increased communities' vulnerability through malnutrition, exposure, social stress, and destruction of sources of medicine and capacities for palliative care".