Complex sentence: He was music director of the Buffalo Philharmonic Orchestra from 1971 to 1979, and from 1971 to 1977 conducted the series of Young People's Concerts with the New York Philharmonic.
Split into simpler sentences: He was music director of the Buffalo Philharmonic Orchestra from 1971 to 1979. During much of this time (from 1971 to 1977) he also conducted the series of Young People's Concerts with the New York Philharmonic.