I have also heard, b4 Palakkad was a part of Tamil Nadu and Kanyakumari a part of Kerala....then it changed.... Probably the song Palakkad pakkathile also shows that(not sure)
True! When they drew the state borders in the 1950s after independence, Palakad permanently went to Kerala and Kanyakumari went to TN. Palakad had been the border between 2 language speaking Presidencies in pre Independence time- Madras Presidency and Travancore Presidency😃