The Iroquoian languages are a First Nation and Native American language family. The language family includes Ganien'keha (Mohawk), Honontahonon (Seneca), Onei'ute (Oneida), Onondaga'te (Onondaga), Kayo'kwen'honon (Cayuga), and Skaroren (Tuscarora) – an endangered language, as well as Southern and Laurentian branches, including many extinct languages, but also Tsalagi (Cherokee), which retains native speakers. Pronunciation systems are diverse; Seneca refer to the Six Nations as 'Haudenosaunee' and Mohawk as 'Rotinonshonon' or 'Lotinonshonon' depending on dialect (Western and Eastern as opposed to Central). 'Mohawk' is an offensive Algonquian term, meaning "cannibal" (Apenaki – Mohowawog "cannibal"). Ganien'keha does not use any labials (m,b,p) and uses an r/l as in many Indic[clarification needed] languages, with fewer than 15 actual letters, but a number of consonantal combinations. Seneca has several letters that are not used in Eastern Iroquois languages, for over twenty letters, with few consonantal combinations. All Iroquoian languages today use nasals and glottal stops. Also, most are tonal languages with long and short vowels not found in English.

The oldest archaeological remains identifiable as Proto-Iroquoian/ Great Lakes culture occur at 8,000 to 8,500-year-old strata in the Eastern Great Lakes region. The first Iroquoian villages occur in Central New York, in the area of present-day Onondaga, at about 7,500 years ago. Dispersion of villages and language groups from this are to Ganien'ke, in Herkimer County on the Hudson River, NY and to the shores of Lake Ontario in Seneca country occur about 6,000-5,000 years ago. From Mohawk arose the Oneida dialect and from Seneca arose Cayuga. The Tuscarora are a Southern branch nation whose migration to North Carolina area is evidenced at about 400–500 years ago, and who were driven North by attacks from British and Algonquian allies at the end of the 17th century. Cherokee is evidenced to have separated from Northern nations about 600–800 years ago. Existence of a Susquehannock language is theoretical and not documented. The archaeological evidence of Iroquoian dispersion tightly matches Six Nations traditional history. References: Six Nations League Center for Culture and History; Snow, Gehring and Starna, "In Mohawk Country," Syracuse Univ. 1996;E.M. Ruttenber, "Indian Tribes of Hudson's River to 1700, orig. pub 1872, republished by Hope Farm Press, 1992; Starna, "The Iroquois," Cornell Univ. Press, 1998;Driver, "Indians of North America," Chicago Univ. Press, 2002; Ganienke'haka Onkwawen:na Raotitiohkwa.

Iroquoian languages have a theoretical relationship to Dakotan languages. Noam Chomsky theorized a relationship with Sino-Tibetan languages.