Thanks, for all the amount of details and vage points I through at you it looks like it turned out alright. A bit off on the characters shadow sizes and the right characters anatomy and line art, I quite like how this turned out.
The Idea came from from two places. The anthropology song thats currently being worked on because I keep thinking history every time I hear it, and the history class I'm taking this semester when we had to read about the Paleolithic era (old stone age) which was the time before we started farming (hunting & gathering and continusally moving). Apparently during that time humans in the Americas hunted all the horses to extinction which made quite sad, but it got me thinking what would have Equestria been like during its own such time. Would the immortal princesses be around? a lesser intelligent but greater strength pony species/race existing? etc etc.
The idea took form when a few of us random bronies were joking how everything happened a thousand years ago, how all the good stuff was right at that point, and on and on. The streamer we were watching was looking at his requests when I suggested the cave pony idea, but it ultimately came down to other people's requests being first and it generally wasn't heard, which is when I said I'm going to make it a thing. Being I can't draw and MrRowboat needed $$ to fix his car I desided why not. And thats how the idea came to be.