Passage: Ensemble Studios released an expansion for the game named Age of Empires III: The WarChiefs on October 17, 2006. It contains three new native civilizations that can be completely controlled: The Iroquois Confederation, the Great Sioux Nation, and the Aztecs. New content for existing European civilizations, maps and gameplay additions (such as the "revolution" feature, in which players can "revolt" from their mother country and start an active military coup in the game) was added.

Question: When was the game expansion released?
October 17, 2006