The Kuiper belt is a belt that extends from the orbit of the planet Neptune.
It looks like an asteroid belt, only it is much bigger and more massive than the asteroid belt.
If they are said to be comets that come from there, they clearly come from the "Spread Disc" in the Kuiper belt, because there are most of the objects begging in the belt.
The Dutch-American astronomer claimed that this belt existed.
It is said that possible planets were also discovered in the Kuiper belt, but nothing has been confirmed.
The only thing confirmed was Sedna, which is a dwarf planet, meaning theoretically it is, but not everyone says it is a dwarf planet, it is a possible dwarf planet.