Why does Tamil Nadu in the past had so many landslide election results between DMK and ADMK?

Why does Tamil Nadu in the past had so many Landslide decisive election results? Hey everyone, I am a North Indian who recently started taking interest in South Indian politics. Some time ago, I was looking at the past election results of Tamll Nadu, and noticed the spectacular amounts of landslide victories for botb DMK and ADMK. Such as DMK ADMK 2011 LA Elections- 31 203 2006 LA Elections- 163 069 2001 LA Elections- 37 196 1996 LA Elections- 221 004 1991 LA Elections- 007 225 1989 LA Elections- 150 027 The staggering amount of complete landslides (especially 1991-1996) is something that is really uncommon and the fact that it has often times turned around towards the opposite party makes it more interesting. Was it the leadership? Policies? General political wave? I would really appreciate it if someone native from the state itself who has experienced/witnessed all of these events would provide an explanation. Thanks