Migration diagram for major Haplogroups

 The migration diagram for major Haplogroup and Castes shown below

As shown in the diagram many castes are recent formed during Medieval period from multiple ancient Sources. Gangetic Brahmins in UP look include recent mix from multiple sources post Buddhist era especially Uttarkhand and Bhumihars and parts of UP. Whereas Southern and Eastern Brahmins are more from the earlier era. The Middle castes that are Farmer/Ruler category are also very highly mixed. The Kshatriyas are from multiple waves of input some of whom harbor the Eneolithic Steppe. There was also an North african migration in very ancient times which brought in new crops and technologies, even today we see some Haplo T and very small E present in parts of India.

 

The oldest migrations are 

  H1 from 35000BC, 

J2a from 8000BC, 

O2 from 6000BC, 

J2b from 4000BC, 

L1 from 2000BC and 

R1a/R2 from 1500BC.

The migrations at the Neolithic time probably looked like this,

From Reich lab figures for latest dates of caste formation and their admix