Early Moriori formed tribal groups based on eastern Polynesian social customs and organisation; later, a prominent pacifist culture emerged; this was known as the law of "nunuku", based on the teachings of the 16th century Moriori leader Nunuku-whenua). This culture made it easier for Taranaki Māori invaders to nearly exterminate them in the 1830s during the Musket Wars; this was the Moriori Genocide, in which the Moriori were either murdered or enslaved by members of the Ngāti Mutunga and Ngāti Tama iwi. Killing or displacing nearly 95% of the Moriori population, the genocide was one of the deadliest in human history. The European colonial authorities at the time became notorious for not only doing nothing to prevent what happened, but claiming that the Moriori were extinct.