always has been since 1895 with violence even starting to appear in films in 1903 with "The Great Train Robbery", before in 1895 was the film "The Execution of Mary, Queen of Scots".
Even worse, the first R rated movie appeared in the US called "Greetings" which was released in 1968 with Severe Sex and Nudity (meaning it would be pornographic), mild in violence, moderate in offensive language, and moderate in intense scenes.
I'm not sure what the first r rated film to have severe violence, but I do know it would have been before the 1990s