The Kuiper Belt was named after Gerard Kuiper (1905-1973) a twentieth century Dutch astronomer who In 1949 hypothesized that the solar system had formed by the condensation of a large cloud of gas around the Sun. Included in this hypothesis was a disk-shaped belt of comets orbiting the Sun at a distance of 30 to 50 AU from the sun. This was verified in the 1990s, and it was named the Kuiper belt in his honour.
At this distance ingredients like water, CO2, methane,and ammonia are frozen into cosmic snowballs.
Estimates range between thousands and billions of these small objects.
Until the 90's only Pluto,its moon Charon and a few comets were known to be there. Since then close to a thousand have been found. A few have even been found to be large enough to be categorized as
Dwarf Planets.
However looking for something so small, and so far away is not easy.
One project The Taiwan-America Ocultation Survey spent two years trying to see if these would occult background stars. After over 200 hours of close observation they came up empty. They therefore concluded that there are relatively few kilometer size objects in the region.