I'm unable to say but around the mid-1960s was when it turns to "the more encompassing international style" of rock music
Perhaps in the 1950s and mid 1960s, as this was the time when the ''more encompassing international style'' of rock music came about
I love rock and roll music.  Do you know much about the genre? It's a genre of popular music that came about in the United States around the late 40s/early 50s, from African American musical styles, like gospel, jump blues, jazz, boggie woogie, and with some country music thrown into the mix! So it has a lot of influences.  When was rock music the most popular?
According to Greg Kot, ''rock and roll'' refers to a style of popular music originating in the U.S. in the 1950s prior to its development by the mid-1960s into ''the more encompassing international style known as rock music, though the latter also continued to be known as rock and roll.''