The griffins have been part of stories, myths and legends for thousands of years.
Hunted because of their abilities and supposedly healing feathers and farsighted eyes, they went into hiding at some point. But not just in the mountains, which were once very beloved places for them. Humans explored almost every spot on earth, so that they no longer felt safe anywhere. So they moved further away from us than we could ever imagine.
Now that they are almost forgotten and they are no longer hunted, they slowly return from their universes and dimensions. Over the generations they have evolved and changed. Their appearance has long since become more diversified than before.
Even though the Griffins have avoided the earth for many of their generations, it is still their home.