This is discussion archived from a time before the current discussion method was installed.
Kendra Kirai: I have to wonder about this...couldn't there be areas where asteroids have 'clumped together' naturally, or via external forces? Pretty much every example except the real life ones are in times where interstellar travel is commonplace, and some of them can exert tremendous forces just passing relatively nearby, plus there's the speeds involved...to get anywhere in a star system within 'weeks'', you'd have to be going at a pretty good fraction of the speed of light...and this would be after who knows how many years of mining, accidents, warfare, and even simple trash disposal has shuffled things around and turned big rocks into lots and lots of smaller rocks. In areas which are naturally more dense, and stuff seen is crashing into each other, it could have been triggered by a ship passing by and causing the chain reaction of stuff moving around. Space is not static, after all, it's just hard to get stuff of any real size going.
It's theorized that our asteroid belt was once a planet between Mars and Jupiter, which met with some unknown destruction. Over the billions of years, much of the 'loose' stuff that didn't find a stable orbit has fallen into Jupiter, the sun, or any of the other moons or planets. (Heck, it's even possible, though this is just my own half-assed on-the-spot theory, that Phobos and Deimos are chunks of this lost planet that ended up in a stable orbit around Mars.) Who's to say that in other star systems, there's orbital paths of rock that never got the chance to coalesce into a planet, due to other planets being closer, there being a less stable orbital system, a 'rogue planet' meandering through and getting pulled into an orbit which ended up on a collision path..the universe is, after all, incredibly old, and there's 'trillions of stars, any of which could have planets with asteroid belts...probability states that there has to be at least a couple'' of these asteroid thickets, even if only in localized pockets and not an entire "belt".
S'just my thoughts, though, and I appear to be made of Handwavium.
Kuciwalker: No. If you had an asteroid field with the density of e.g. the one in TESB, the asteroids would be constantly running into each other and breaking into smaller and smaller pieces, until it was more of a sand field. The chance of the asteroids all moving exactly within the orbit and having no relative velocity is essentially zero; moreover, even if it were like that, gravity would quickly end that condition.
