Having done a 40-some-odd-page senior project in college on the lineage of Flamenco, and exactly how it was shaped by the cultures it encountered throughout it's history, I gotta step in here. The Gitano (Spanish Gypsies/Rom) almost certainly came from North-East India, Rajasthan, and have common roots with modern Kathak Dance.
HOWEVER, the musical styles are extremely disparate, at this point in time. The Gitano left Rajasthan well over a thousand years ago. Also, my dance-officianado friend assures me that the similarities between Flamenco Dance and Kathak are muted at best, and that there are much more similar styles to each... I can't personally speak to that, but that's what she says, and she has studied Kathak dance in India for some time...
Ok, rant aside, your best bet is to pick two, random, completely disparate cultures, and then show how they both focus on melodic content, have scale-systems based around the harmonic series, generally have a consistent modality or center point for melodic direction, and a relative lack of any strong concept of complex harmony.
As long as you don't pick contemporary genres, and you stay away from Western Art Music, that's going to be largely true of every traditional folk music (Pre-western Imperial Sprawl) from Celtic, to Hungarian, to Japanese, to Chinese, to Indonesion, to Indian, to South African, to Bedouin...
Have fun exploring!
EDIT: If you *are* interested in the realtionship between Indian and Gitano music, that paper I wrote is right
here.
It's a little longish, but it's a starting place, and the bibliography has good resources for further reading, and there's also a list of suggested listening from the various cultures mentioned.