The Sanatana Dharma was an intruder into Tamil Culture, it was imposed by the Brahmins who crossed over th India through the Khyber Pass, say the Rationalists and The self-styled scholars of Tamil.
Yes , it was imposed to such an extent that the early Tamil literature Ahanaanuru records that the Chera King Udiyan Cheralaathan offered Tharpana to the people killed in the Mahabharata war.
He also fed both the Kaurava and Pandava Army, as a Third Umpire.
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அலங்கு உளைப் புரவி ஐவரொடு சினைஇ
நிலம் தலைக் கொண்ட பொலம்பூந் தும்பை
ஈர் ஐம்பதின்மரும் பொருது களத்து ஒழியப்
பெருஞ்சோற்று மிகுபதம் வரையாது கொடுத்தோய் – புறநானூறு 2.-Poet Maamoolar‘Provided Unlimited Food for the Battle by The Kauravas’
2.Performed Tharpana and Sraddha.
‘ “துறக்கம் எய்திய தொய்யா நல்லிசை முதியர்ப் பேணிய உதியஞ்சேரல்”
Udiyan Cheral performed obsequies for the ancestors’-Ahanaaanuru 233
His contribution in feeding the army was acknowledged so much appreciated that he was subsequently called with Prefix ‘Perunchotru Udiyan Cheralaathan’
Perunchotru Udiyan means one who fed vast quantities of food to People.
Reference.