[xSkullheartx]

I think it was a destroyed city,but due to the Forest growing out of control. Yggdrasil made the drivers,right? Maybe they made them to stop the forests growth. Maybe they know that the forest will overgrow and devour the city,which is why they are trying to stop it.

The reason the Beat Riders exist is because of exactly what Ryouma said,they're test subjects,but because the "bad guy" said it,right away the audience is led to think that it's a bad thing.Maybe being the test subject is a good thing.Maybe Yggdrasil is mass producing the belts so everyone has a way to defend themselves,and they don't want the Beat Riders to have the belts because they don't want teenagers getting hurt.