Complex sentence: Dallas remained one of the NFL's top teams for the remainder of the 1960s, easily winning their division in 1968 (with a 12--2 record) and in 1969 (with an 11--2--1 mark).
Split into simpler sentences: Dallas remained one of the NFL's top teams for the remainder of the 1960s. The Cowboys easily won their division in 1968 (with a 12--2 record) and in 1969 (with an 11--2--1 mark).