"References to the story of Rama occur in the earliest part of the Sangama literature of Tamil Nadu, dating back to a period almost as old as the Ramayana of Valmiki. [... a theme from the Ramayana] forms the subject-matter of a terracotta representation from Kausambi, ascribable to the 2nd-1st century BCE."
January 1, 1970
https://en.wikiquote.org/wiki/Historicity_of_the_Ramayana