How did the "jazz period" start?

please help..

Buddy Rich and Gene Krupa. Also, Benny Goodman as well. Duke Ellington, Charlie Parker, Billie Holiday, John Coltrane, Dave Brubeck, Ella Fitzgerald, Nina Simone, Lena Horne

From Rag Time

For me, it started in the late 40s until the 70s.
The best was around the early 60s.
Hey, I had the chance to see live: Louis Armstrong, Miles Davis Quintet, Duke Ellington Band, Count Basie Band, Maynard Furguson, The Double-Six de Paris, Art Blakey's Jazz Messengers.
Beautiful memories!