Mass slaughtering other people, by genocide, is standard practice for vast numbers of people, across the centuries. Crusades, wars, conquest, expansionism, slavery, "Manifest Destiny," "Lebensraum", whatever excuse, any will suffice.
America at Columbus' time had had 150,000,000 natives, “cent cinquante millions d'hommes.”
~Dr. Hippolyte A. Depierris, Physiologie Sociale (Paris: Dentu, 1876). Another source says 100 million ~ George Monbiot, "Review of Avatar (The Guardian, 11 January 2010), citing Prof. David E. Stannard, American Holocaust: The Conquest of the New World (Oxford Univ. Press, 1992) (Excerpts). See also his video lecture American Holocaust: The Destruction of America's Native Peoples (Vanderbilt Univ., 30 Oct 2008).
The Spanish conquistadores (are) reported to have killed tens of millions of Indians in the 1500's, via smallpox, anthrax, brucellosis, leptospirosis, trichinosis, and tuberculosis."
~Charles C. Mann, 1491], Atlantic Monthly (#3) (March 2002)
Note that "it was America that amassed a history of xenophopbia and genocide that impressed even Adolf Hitler. 150 years later nearly 90% of those Native Americans were gone, mostly due to diseases brought by the white invaders. After 1630, white Americans resorted to more aggressive genocide. Aside from the dozens of major anti-Indian wars sponsored by the U.S. government, American citizens in general . . . often went out of their way to slaughter Indians. Innocent Indians. Indian women and children asleep at night in their tipis. Even Indians under flags of truce. . . . 'poisoned meat and drink, smallpox-infected blankets (The first example of germ warfare in the U.S. was in 1763 when some of the European colonists gave friendly Indians a number of blankets that had been infected with smallpox, causing many deaths) , booby-trapped bodies, cannon charged with slugs, dogs unleashed on captives, and the execution of the wounded, women and children. . . . Indian women with children were dispatched with no more compunction than stray dogs. . . . Some white men . . . wrote a disgusted . . . missionary . . . "kill Indians just to try their pistols."
~ Prof. Michael P. Ghiglieri, Ph.D., The Dark Side of Man (Reading, MA.: Perseus Books, 1999)
Poisoning has a long record of being used against one's enemies. For example, in 1623, British negotiators of a treaty with Indians near the Potomac River, under Chief Chiskiack, offered a toast "symbolizing eternal friendship." The British poisoned the Indians' food. The Indians (chief, family, advisers, and two hundred in the retinue), then died immediately of poisoning!
~J. Leitch Wright, Jr., The Only Land They Knew (New York: Free Press, 1981)
By the 1890's, only about 250,000 Indians survived, says Richard Thornton, American Indian Holocaust and Survival (1987), and Richard Maybury, The Indian Wars (2006), citing Stannard, American Holocaust, supra, p. 146.
The U.S. Cavalry in the late nineteenth century was primarily a government instrument of genocide. As directed by Washington, D.C., it nearly extirpated all Plains Indians . . . By 1864, for example, General Philip Sheridan voiced U.S. policy this way: 'The only good Indian I ever saw was dead.' This was reworded to become the maxim of the U.S. Army: 'The only good Indian is a dead Indian.' A more concise formula for genocide would be hard to find.
The U.S. had used genocide against the Indians in the U.S., under politicians that treated Indians like they'd treated blacks. Remember Dred Scott v Sandford, 60 US 393, 407; 15 L Ed 691, 701 (1857), people with "no rights which [anyone] was bound to respect; and . . . might justly and lawfully be reduced to slavery for his benefit . . . ." Slavery included genocide, killing tens of millions. Killing Indians, expanding slavery, taking others' land and property, both were standard U.S. polices, for American "Lebensraum," expansion, "Manifest Destiny."
Hitler called Germany's "Manifest Destiny" Lebensraum. As a matter of perspective, America's Lebensraum policy, "Manifest Destiny," had violently expanded the US from a sliver of 13 colonies along the Atlantic, to continent-wide over the dead bodies of Indians, Blacks, and Mexicans.
Hitler claimed to have gotten his inspiration for the "final solution" from the extermination of Native Americans in the U.S.
Some "methods [of the 'Final Solution'] were inspired by the U.S. government's subjugation of the American Indian."
Hitler "admired the [U.S. approach] for the Indians in the Wild West; and often praised to his inner circle the efficiency of America's extermination—by starvation and uneven combat—of the [Indians]."
~John Toland, Adolf Hitler.
The U.S. has the world's record for genocide of Indians, about 15,000,000.