Ariz. Const. art. 20, § 5

Fifth. Fifth. The lands and other property belonging to citizens of the United States residing without this state shall never be taxed at a higher rate than the lands and other property situated in this state belonging to residents thereof, and no taxes shall be imposed by this state on any lands or other property within an Indian reservation owned or held by any Indian; but nothing herein shall preclude the state from taxing as other lands and other property are taxed, any lands and other property outside of an Indian reservation owned or held by any Indian, save and except such lands as have been granted or acquired as aforesaid, or as may be granted or confirmed to any Indian or Indians under any act of Congress.