Complex sentence: In 1971 MNW was formed, and in the middle of the 1970s around 50 independent record companies existed, and during this decennium the prog movement had a strong position in the musical landscape of Sweden.
Split into simpler sentences: In 1971 MNW was formed, and in the middle of the 1970s around 50 independent record companies existed. During this decennium the prog movement had a strong position in the musical landscape of Sweden.