Onderon is a Terran Federation colony world.
Prior to the 27th century, the planet was home to a civilization whose technology was equivalent to Earth in the 20th century. However, the Onderonians were wiped out in a war which devastated their civilization.
The planet was soon colonized by the Terran Federation during its Gilded Age. Originally with the purpose of studying ancient ruins on the planet, Onderon eventually grew into a prosperous colony world with a large and diverse population of 500 Million.