Just how far did Freeza's empire reach?

[caejones]

Why would the Kais step in? Freeza wasn't breaking any universal laws. He was well within his rights as a mortal to conquer the lower universe if he felt like it.

Then why did they step in with Buu?

I'm assuming Buu attacked the Kaioshin realm, then went off to try and wipe out existence. Big, big difference from subjugating a few billion people.

[Xyex]

I doubt it stretched anywhere outside of the North quadrant, in fact it was probably less than a quarter of the North galaxy otherwise the Kai's would have stepped in.

Why do people keep thinking the Kais step in and kill mortals at a whim? Did Kami try and stop Pilaf or the RRA? Did Kaio step in to stop King Piccolo? Raditz? Maybe the Kais should have wiped out the Saiya-jins when they tried to take over Planet Plant, thus killing off Goku's family before Goku was even born?

It is not the place of the gods to interfere in mortal life. The Kais watch over the universe, safeguard it from utter destruction. They are not the inter-galactic police.

Why would the Kais step in? Freeza wasn't breaking any universal laws. He was well within his rights as a mortal to conquer the lower universe if he felt like it.

Then why did they step in with Buu?

Because of the following:

1) Buu was not a mortal, he was a super natural being.
2) Buu was not just a mortal living out his life, but an engine of destruction designed to destroy the universe.
3) Buu attacked them first, not the other way around.
4) Buu's a 'god killer', that always gets the attention of the gods.

Again, assuming that just because Kaioshin stepped in with Buu (something that's a threat to the very existence of the universe itself) that the Kais make a habit of doing everything for the mortals is ridiculous. The same thing occurred on Earth, if you'll think about it. Kami did not interfere in the course of mortal affairs until Piccolo came along, a supernatural being with more power than he himself had.

Why would the Kais step in against Freeza? Why not step in against the Saiya-jins? The RRA? The Androids in Trunks's time? The only time a Kai ever interferes in the mortal world is when Kaioshin comes along to help deal with Buu, a cosmic threat. Hell, King Kai doesn't even just go about doing things willy-nilly with Earth. He gives aid specifically to his pupils, but not to anyone else. A minor bending of the rules that wouldn't even be possible of his pupils were normal and actually stayed dead like everyone else in the universe.

[Dayspring]

Why would the Kais step in against Freeza? Why not step in against the Saiya-jins? The RRA? The Androids in Trunks's time? The only time a Kai ever interferes in the mortal world is when Kaioshin comes along to help deal with Buu, a cosmic threat. Hell, King Kai doesn't even just go about doing things willy-nilly with Earth. He gives aid specifically to his pupils, but not to anyone else. A minor bending of the rules that wouldn't even be possible of his pupils were normal and actually stayed dead like everyone else in the universe.

Kaio even mentions that he should be impartial when Krillin goes to kill Vegeta, but that he's glad Krillin's going to kill him because of how the Saiyans terrorized the Universe. It's the same with Freeza: the Kaio/shins were hoping he'd die, but they had no real right or reason to interfere. Freeza only had the potential to mess up the reincarnation process by destroying all life in the Universe, not the desire. Boo not only had the power to do it more quickly, but also the motivation, as well as the potential to go after the Afterlife and Kaioshinkai.