Upvote:4
As you say, cremation in India is first attested in the archaeological evidence with the Bronze Age Cemetery H culture dating from about 1900 BC. This is considered to be the formative stage of Vedic civilization.
Changes in burial practices are often seen as evidence for the arrival of new populations (so-called "invasion hypothesis").
The Rig Veda is one of the oldest extant texts in any Indo-European language, with philological and linguistic evidence indicating that it was probably composed between c1500 and 1200 BC. The fact that it declares that their forefathers were either cremated or buried doesn't actually conflict at all with the archaeological evidence.
A useful recent (2014) text for those trying to understand the Aryan migration theory is The Elusive Aryans: Archaeological Search and Vedic Research; The Origin of the Hindus by Pradhan S. V.
Upvote:7
I just want to know is there any evidence of the practice of burning dead bodies existed in India before 1900 BC
It matters very little if there was anecdotal evidence prior to 1900BC. What matters is that, per your own question, the archeological evidence found to date suggests that cremation went from anecdotal or non-existent to widespread after that, while burials went from widespread to rare.
This suggests that something occurred around then that was significant enough to change local habits. One contender (the main one?) to explain the shift is that newcomers, the Aryan, introduced new funeral practices that eclipsed existing ones.