Khasi man from a vilage near Mawlynnong in the East Khasi Hills, in Meghalaya (India)

The orange color of his teeth is from chewing Betel nut. Areca palms trees (Betel trees) grow everywhere around here so Betel nut is consumed by all the locals (men and women), as a psycho-stimulating and euphoria-inducing drug.

For more info about Betel nut, go to en.wikipedia.org/wiki/Betel.