The evil creepy G1 ponies killed them all. So they're all extinct. The G3 ponies saw the violence were like "NOPE NOPE NOPE TOO MUCH VIOLENCE" so they used their stupidity to make sure no one knew what they were. Now, G1.2 ponies built a portal to the humans in one of their highschool science fairs.
KIDS TAKE NOTES, TEST ON MONDAY GOD DANGIT!