Why is it not correct to divide indian history on the basis of religion?

I am going to assume you are referring to the history of the Indians from India.

Most people have done little research into the history of India's background. However the history of what is now referred to as India intertwines with Biblical history, especially in what's called the Old Testament.

All humans in one way or another have been affected or infected by religious customs and beliefs from the creation of the first humans until now. However customs and beliefs are the way people have chosen to worship or do things based on their desires, not based on their creator's command or insistence.

The Bible says at, (2 Timothy 4:3,4) "For there will be a period of time when they will not put up with the wholesome teaching, but according to their own desires, they will surround themselves with teachers to have their ears tickled. They will turn away from listening to the truth and give attention to false stories.

This has happened and is happening even today. Whether you are referring to the Indians from India or The Native American Indians, the answer would be the same, it would still apply.

Finding out what the creator's original plan for humans is, no matter who we are, would benefit all of us. Then we could worship God according to the way He wants to be worshiped, and not according to how we feel we should worship Him.

Doing so would put us in a position of favor, where God could make the statement that he made in the Bible at, (Genesis 1:31) "After that God saw everything he had made, and look! it was very good".