@ChIkEn NuGrEt
The elephants were received by the zoo some years ago, after a rescue from a circus. I think there were no plans to keep elephants there at the time, so they had to hold them in this exhibit. The mix seems to have gone well, and they kept it this way regardless of geographical accuracy. I tend to think the buffaloes were added later, and I hope they find another place to put their hippos. This way, the enclosure would be composed only of asian species (without considering the smaller critters, such as sliders).