Krishna slew king Kulasekhara Pandya by striking his breast against his, and moved down the Kalingas in battle (5:48).
King Sarangathdwaja wanted to attack Dwaraka to avenge his father's Death, the Pandya King after obtaining weapons from Bhisma, Drona, Balarama and Kripa.
However wiser counsel prevailed and he dropped the idea.
Later he fought alongside the side of the Pandavas against Drona(7:23).
He was rate as an Athiratha by Bhishma( (5,172)
During the Mahabharata Days the interaction between the South and the North were more intense and frequent than what it was during the Ramayana Period.
Lord Krishna attended the Tamil Sangam,Conclave of Poets held at Kavatapuram.
He was a special Invitee.
Here is yet another proof that the South was a part of Sanatana Dharma, Aryan Dravidian Theory is a myth and the people of North India and South India were a part of the Glorious Bharatavarsha.
Rama's marriage was graced by the Kings of South India.
Damayanti's Swayamwara had Tamil Kings presence.
Lord Krishna married a Pandya Princess.
Arjuna went on a pilgrimage to South and married a Pandya princess.
Chola and Pandya Kings fought on the side of Pandavas in The Mahabharata War.
Chera King fed both the Kaurava and Pandava armies and performed Sraddha , Obsequies for those killed in the war.
The Vedas mention Lord Muruga as Skanda.
Steeds that were all of the hue of the Atrusa flower bore a hundred and forty thousand principle car-warriors that followed that Sarangadhwaja, the king of the Pandyas. Mahabharatha 7.23
In return, Malayadhwaja pierced the son of Drona with a barbed arrow. Then Drona's son, that best of preceptors, smiling the while, struck Pandya with some fierce arrows, capable of penetrating into the very vitals and resembling flames of fire. Mahabharatha 8:20'
Add to this the Bhagavatham stating that the Ancestor of Lord Rama, Satyavrata Manu having migrated to North with two sons to establish a Kingdom in Ayodhya."
This is a clear indication of the culture from the South moved to North , to Sarasvati Valley and later Indus Valley.
Then there is the Tamil script being found in the Mohenjo-Daro.
One batch of migration from the south took place towards the Sarasvati .
What about the next?