Part of the Ila Arun singing portion of Kata Kata is based on a known Rajasthani folk tune, also previously heard in a Hindi film with the song titled "Pallo Latke". The other choral parts are purely Rahman's melodies.
I think it's cool how Rahman used the original Rajasthani folk tune and blended it in so nicely in Kata Kata. Rahman did something similar in the songs Mercury Pookal and O Paalanhare, using a known melody sung in traditional Bhajans and using it tastefully and delicately in both songs, blending his original tune with the traditional melodic verse.
