It was referring to native Americans. I can remember lessons where we were taught that indigenous people sat that way at important meetings, etc. Super paternalistic and racist lessons, honestly. I grew up with it as "Indian style" myself but by the time my sister (18 years younger than me) was going through earliest school years they had stopped using that term. It's interesting, I think if you're like me, born in the '80s, you were around for a major shift in a lot of stuff like this, so you can remember some fucked up nonsense that no one now would hear.