We can't say for sure. Both of our theories are still disputed b/w scientific community. But I think the migration happened. Jat's father side is related with Scythians as of the DNA tests and mother's side from Native North Indians and West Asia. Many Jats have light colored eyes and as we know light colored eyes are not native to South Asia. My friend's brother lives in London and he is a Jat too. He had his DNA test done from a site 23andme.com . It told him that he is 74% South Asian, 23% Central Asian, 2% West Asian and 1% Middle Eastner. I am also considering a DNA Test. If I will have it done, I would love to share it with you.