PSA for anyone who heard the myth that Two-Spirit genders were invented at the 1990 transnational gathering of American Indian Gays and Lesbians:
Third/fourth/fifth/sixth/etc. genders have been established in many Indigenous cultures for a minimum of hundreds to thousands of years across all regions and within all associated economic structures of Turtle Island.
Academia formerly settled on the term "berdache" for these culture-specific genders in English. Because this term is understood to be a gendered sexual racial and ethnic slur, it was necessary to replace it. During that 1990 gathering, Cree Elder Myra Laramee dreamed of seven spirits who shifted between male and female, two of whom declared her to be Niizh Manidoowag, which translates into English as Two-Spirit. This was presented at the gathering and adopted as the replacement English umbrella term for preexisting Indigenous culture-specific genders.
Two-Spirit is not a replacement term for Indigenous language terms and should not be prescriptively applied to individuals who do not identify as such. "Two-Spirit" also does not directly correlate to "Indigenous nonbinary;" some Two-Spirit people may also identify as nonbinary or binary trans (and/or other terms) in English, but Two-Spirit is a broad umbrella term for all traditional Indigenous gender variant identities.
Enforcement of the gender binary is inherently an act of anti-Indigenous racism and cultural chauvinism.