They are completely different species that would never interact in the wild. Our desire to keep things as natural as possible is part of it. Additionally, they have vastly different temperaments. What is seen as play for African elephants could be seen as aggression.

Why separate habitats? Do Asian & African elephants not mix well together? Sorry if I missed a post on the topic.

I did actually respond to your question earlier. Here’s what we said:
There’s no way to know if they’ll understand each other, though elephants have an amazing ability to communicate, so there’s always a possibility. They’ll certainly know the others are there, since elephants can sense things for miles at a time. They will have separate habitats at different locations at the sanctuary, so they won’t see each other.