The Briscoe’s “Tejano Legacy: Another American Origin Story” exhibition covers 400 years of culture and history. Credit: Courtesy Image / Briscoe Museum

The mythology of the American West doesn’t begin with the archetypal American cowboy. It surfaced centuries earlier through the people, cultures and traditions that shaped ranch culture before the U.S. was established.

In its most ambitious exhibition to date, San Antonio’s Briscoe Western Art Museum this Saturday is opening “Tejano Legacy: Another American Origin Story,” an exhibition that covers 400 years of culture and history.

The collection of art, artifacts and ephemera opens just in time to celebrate Día Nacional del Vaquero (National Day of the Cowboy), a community celebration that kicks off the run of “Tejano Legacy”with charro demonstrations, folklórico performances, roping activities and full access to the exhibition, which runs through Jan. 18 — along with “Selena Forever/ Siempre Selena,” which runs through Jan. 4.

Free with online registration, 10 a.m.-4 p.m. Saturday, July 25, Briscoe Western Art Museum, 210 W. Market St., (210) 299.4499, briscoemuseum.org.