A western is a type of book, film, or holoprogram based on the Western United States of America during the 19th century, a period later known as the Ancient West. (ENT: "Horizon"; TNG: "A Fistful of Datas")
Charles Tucker once speculated that Zefram Cochrane spent his nights reading "about cowboys and indians". (ENT: "Shuttlepod One")
Deanna Troi was a fan of stories set during the Ancient West. Her father, Ian Andrew Troi, often read her such tales when she was a child.