are you implying the fairer Indians (north indians) are caucasians?
It is not possible to define South Asians/Hindus into a race, due its long civilizational existence and inter mingling with world population for millenniums.
Obviously the lighter Indians are white just like Sfardic Jews and other Middle Eastern/and or Central Asian peoples.
What you are referring to regarding mingling is true. That's why darker Indians exist. They mingled with the Australoids. Also, some Indians are Oriental.
I used to think Indian was a race like Hispanic. But both Indian and Hispanic are not races. Indians come from many different races as do Latin Americans.
There are only 4 human races and anything else is only a mingling of 2 or more of those races. Obviously some areas have more mingling than others. India sits between white countries to the West and Oriental countries to the East. It's just like North Africa sits between white European countries to the North, white Middle Eastern countries to the Northeast, and black Sub-Saharan countries to the South. The result in the case of North Africa is that many Arabs are part black but the original Arabs from Arabia were white like other Middle Eastern peoples.