Let's talk about the politics in ATLA. I would like to start out with talking about the Earth Kingdom. If my memory serves me correctly I don't think they ever talk about who exactly has total power over the Earth Kingdom. Is it the king from Ba Sing Se? Then how is Bumi a king? Is it set up like how Germany was? Where their princes who rule certain areas and one big head guy (who actually didn't have a lot of real power).

The Earth Kingdom is a City-State nation. That's how two different cities can have different rulers. Such as King Bumi and King Kuei. Or earlier (before Aang's time), when Kyoshi was the Avatar, there was Chin the Conqueror and King Kuei's ancestor.

As for King Kuei's predicament, it wasn't his fault that Long Feng was in charge and he was a figure head for most of his life. If I remember correctly and I will find a source for it, Kuei was four years old when he was crowned king. Long Feng was the regent for Kuei until he was of age.

But being a four year old and had to grow up a ruler, Long Feng had many years to basically usurp the throne from Kuei. But Kuei has no power over Omashu. And Bumi has no power over Ba Sing Se.

Well that's interesting and I guess that's why refer to as a kingdom instead of a nation since all the cities aren't unified. So that's mean they can easily go to war with each other and explains why the Fire Nation couldn't take down the Earth Kingdom easily.

That's what did happen during Chin the Conqueror's time. He went to war with other villages and was trying to take over the Earth Kingdom.

Fire Nation couldn't take the Earth Kingdom down so easily because of it's size in general. It's a huge nation for one, then there is that desert, Omashu had held strong for many years, and Ba Sing Se as so many walls it's hard to penetrate it. That's why Azula was more successful. She infiltrated the city unlike what her family had been doing for generations of attacking it head on.

Exactly! I feel like that's an obvious thing to do when it comes to a city that big.