SPOILERS FOR GAME OF THRONES I don't watch the show so I don't know how much this video spoils, Video In Question

First time posting here, hope I didn't screw anything up.

The video says that cannons ushered in a new era of government and society. As much as I like the idea of a single invention changing warfare and governments, I find it a little hard to believe.

Cannons causing the rise of Nation-States? There has to be more to this story. Wikipedia says that even towards the end of the middle ages, many medieval castles still managed to "put up a prolonged resistance".

You know, the more I research this to write this post, the more the video seems to fall apart. I'm still not sure though, so I'll post this anyway.