After they met Ash and Gary talked for a while and quickly became friends.

Gary asks Ash if he will show him around. (Remember, Gary is an Invader, he needs to know more about the planet to conquer it.)

Ash shows Gary the wall that separates the Irkens and the (This isn't earth so they aren't human, but we'll just ignore that and say they are.)

Ash explains that the Irkens have to live in the forests and are forbidden from Human areas. So Ash has never been in the actual city before.

They lean on the wall looking at the human city when Gary says that he has cloaking devices that could make them appear human. Ash doesn't believe him at first, but is then interested.

*Btw, I know I didn't color the wall. The wall is red, sorry for my lazyness.