In the early 1860s, when the United States Congress was considering organizing a new territory in the Rocky Mountains, eccentric lobbyist George M. Willing suggested the name "Idaho", which he claimed was derived from a Shoshone language term meaning "the sun comes from the mountains" or "gem of the mountains". Willing later claimed that he had simply invented the name. Despite this lack of evidence for the origin of the name, many textbooks well into the 20th century repeated as fact Willing's account that the name "Idaho" derived from the Shoshone term "ee-da-how".
The name "Idaho" may be derived from the Plains Apache word "ídaahe´", which means "enemy." The Comanches used this word to refer to the Idaho Territory.