User blog comment:KATANAGOD/CoD Wiki News - March 3, 2014/@comment-10261308-20140307203551/@comment-25494464-20140307220605

30's- Country and Blues

40's- Swing and Jazz

50's- Rock 'n' Roll

These are far from being the same. These genre's dominated these time periods (especially true for the 40's and 50's).