The Earth is very, very old, boasting a long and rich history. However, this does not mean that history has always been kind. The history of the Earth is a long cycle of growth, disaster, and rebuilding. Many times did the race of man experience this ruthless cycle before the time of ponies, leaving lasting impressions on history, including, it seems, their own magics.

It was only a matter of time before somepony found it again.