In the case of indigenous peoples, we're often talking about people who have been forcibly displaced to completely different ecosystems than where they traditionally lived.
The most famous example of this is the "Trail of Tears," where indigenous nations living in coastal Florida were forced to arid Oklahoma, but there are lots of others.
... so while everyone has an environment around them to pay attention to, for many indigenous people, the specific "other-than-human persons" their ancestors interacted with aren't still around.