What happened to Old Equestria

Like a lot of bronies, when I saw MLP:ANG, one question I immediately had was whatever happened to the old Equestria. The characters in the movie talk about the old Equestria like it is ancient history, implying that G5 takes place decades or centuries in the future. But other than that, it is not clear how we got here. There are also other questions like if the ponies are divided again, then what happened to windigoes? Why are the ponies no longer the stewards of their environment, i.e. earth ponies farming, pegasi living on clouds and controlling the weather, and unicorns controlling the sun and moon? How did the ponies become divided under Twilight's leadership? Where did the crystals come from? And what happened to the old Equestria? The YouTuber Sawtooth Waves has already made some rather dark hypothesizes answering these questions, but I have another theory that's less dark, and it all has to do with geography.

MLP:FiM has a well established geography with a map anyone can look up. As such, when we see maps of New Equestria, the parallels between the new and old seem inconsistent. Maretime Bay, Zephyr Heights, and Bridlewood obviously doesn't exist in Old Equestria, but where does these new locations fit? At first, I thought maybe Maretime Bay was built where a city like Baltimare used to be and Zephyr Heights might have used to been Canterlot. However, it seemed like a stretch when you consider the fact that unicorns would have to have a reason to live in a forest and pegasi would need a reason to move to the mountains, which in my mind is a stretch. As far as I currently see it, there is no clear parallel between the geography of old Equestria with new Equestria.

Then it hit me. What if the ponies are actually the descents of colonists. I believe new Equestria is on a continent or planet separate from old Equestria. This hypothesis explains so much. The ponies could have traveled to a new place and built new Equestria, but at some point due to an accident or an enemy attack, they lost contact with old Equestria. The pony races all blamed each other and that's how they split up. The windigoes could be far away on old Equestria, explaining why they don't go after new Equestria. Without the influence of old Equestria, the inhabitants of new Equestria wind up developing their own culture. Even the crystals could easily be a sample of the magic Twilight gave them so they can have have a physical connection to the magic of old Equestria. I don't know about you all, but my theory does seem to answer a lot. What do you think?