Complex sentence: The Tigers hold the series longest winning streak of 6 games from 1960 to 1965, which was also part of a 10-game unbeaten streak from 1960 to 1969 which included a 7--7 tie in 1966.
Split into simpler sentences: The Tigers hold the series longest winning streak of 6 games from 1960 to 1965. That winning streak was part of a 10-game unbeaten streak from 1960 to 1969 which included a 7--7 tie in 1966.