You can use the search keywords period and genre to do a special search which will only return playlists which have this period or genre you searched for. You can combine these keywords multiple times.
For example:
Note, the genre keyword can't be combined with xgenre and likewise the period keyword can't be combined with xperiod. However, you can mix them so that you for instance search for playlists which have the exclusive period 1990-1999 and the genres Hip-Hip and Rap:
You can use the search keywords xperiod and xgenre to do a special search which will only return playlists which have ONLY the unique period or genre you searched for.
For instance if you want to search for playlists with the period "1980-1989" you can use the xperiod keyword like so: Spotify playlists with only 1980-1989 set as period.
Note, these keywords can't be combined with genre and period.