Barca and Real Madrid were close until the start of the 60's and then Real pulled away. Argument can be made that while Real were the best team in Europe, Barca were the best team in Spain in the late 50's. Real had the support of General Franco, who did a Drake. Franco was initially a Atletico fan, but as Real were winning and he hopped onto the wave.
Barca still managed to win 3 Fairs/Uefa/Europa Cups by the mid 60's to Real's 6 European Cups. While the European Cup has always been the king, the Fairs/Uefa Cup and Cup Winners Cup had a lot more respect to their names, compared to now. Probably because European Club Competition was only a decade old.
Between the years Cruyff left as a player to when he was returned as coach. Barca were more of a cup team with 1 La Liga title win in that time frame.