Complex sentence: Leeds United's best period of success was in the 1960s and 1970s under the management of the legendary Don Revie, between 1963--1975, Leeds became feared across the country and in Europe.
Split into simpler sentences: Leeds United's best period of success was in the 1960s and 1970s under the management of the legendary Don Revie. Between 1963--1975, Leeds became feared across the country and in Europe.