Kuiper Belt

A region of the Solar System beyond Neptune believed to contain many comets, asteroids, and other small bodies made largely of ice.

There are trillions of remnants from the early Solar System
Some might come from the Solar Systems other suburbs
That later became the Oort Cloud

http://www.universetoday.com/97126/what-has-the-kuiper-belt-taught-us-about-the-solar-system/