Board Thread:Theories/@comment-27441457-20151225042055/@comment-26932251-20160601025917

"There's no knowledge or resources to construct even an aircraft."

You don't know that. Sure, the wall people lacked the technology to create an aircraft but just you wait, in the next chapter, Ymir is going to return in her spaceship with a detachment of space marines to rescue Eren and the remainder of the main cast!