These are the hills from the opening scene in the TV show MASH.
Filming came to the property as early as 1935 with MGM's Tarzan Escapes when the studio built the treehouse near Crag's Road and Brent Mountain.
When 20th Century Fox filmed the 1941 How Green Was My Valley, the studio took an active interest in the property. While they did have an extensive and large backlot at their main studio location, they were interested in the Crag's property because they envisioned moving their entire studio operation to the Malibu Creek property. The property was purchased by the studio in 1946, but they never moved their studios, probably due to the cost of the move.
The studio later purchased part of the Ronald Reagan Ranch and the Hunter Homestead. It was on the latter property that the house used in Mr. Blandings Builds His Dream House was built--a fully functional house, still standing and in use.
The property was the home to the movie and television versions of Mash as well as Planet of the Apes.
While some sets were built and removed, long standing sets included a ranch set, a Mexican Village, and a Fort, now all gone.
In 1974, the State of California
purchased the ranch and opened it to the public in 1976.