2000 was the last year the Bengals and Colts didn’t meet during the preseason. It has become somewhat of a tradition. It likely manifested because the teams are fairly close together.
Of course, last year the teams met in the preseason, and then they met again during Week 8, which saw the teams undergo several changes between those times. But this season, the Bengals and Colts will meet during Week 4 of the preseason and Week 1 of the regular season.
This is the first time this has ever happened in the Bengals’ history.