The background to my own Traveller Universe.
MANKIND TO THE STARS
When mankindís diaspora to the universe began, it started slowly. The early hyperdrive ships could only travel a parsec in a month, and the time lag hindered rapid response to any problems, if indeed, any knowledge of such reached Earth. However, the realization that interstellar drive testing needed to be carried out at a distance from a mass concentration such as a planet or large star led to the swift development of first the Jump One drive and then Jump Two. The ability to cover a parsec in a week massively speeded up communications, and the initial diaspora began. Begun first by governments, and then with reports of other inhabited planets, large companies, the majority of ships headed toward the Galactic Core, seeking inhabitable planets and trade with the newly discovered galactic civilizations. While the improving hyperdrive ships did the initial scouting, the ability of the Jump Drive ships to respond quickly soon displaced the slower hyperdrive vessels to strictly long-range exploration and scouting.
This replacement of the hyperdrive by the Jump Drive had an unexpected side effect. The hyperdrive ships, especially the slower ones of one parsec a month were sold off cheaply, but with a different class of purchaser. No longer the preferred choice of the large government or corporation, the purchasers were small countries looking for places for their growing population, and small groups looking to escape what they viewed as the restrictions of an over industrialized society: societyís misfits, the malcontents, the discontented, and the adventurers. These groups, especially the small groups looking for planets to call their own, headed not for the Galactic Core, but for the Galactic Rim, seeking unexplored areas or those with no prior inhabitants to contest a claim of sovereignty. Small companies, realizing that the was a demand for knowledge of the Rimward areas, purchased surplus hyperdrive exploration scouts or small surplus trading vessels, and began to head deep into the Rim. The number that did not return simply added more than a bit of spice and adventure to the Rim Scouts, as did the fictional exploits portrayed in prose and video. Tales that became all the more tantalizing by discoveries of vanished civilizations and ruins of much earlier space explorers.
While many of the colonizing efforts failed, or were marginal successes, some did flourish, and provide encouragement for even more efforts. Slowly, out into the Rim, a network of settled planets and way stations developed, giving the Rim Scouts rest and repair bases in the Rim, allowing still more distance exploration. The way stations also functioned as the trading forts and posts of the American Frontier, giving a rest stop for small colonizing groups heading deeper out after unsettled or presumed greener pastures. The efforts by smaller planetary governments to establish colonies deep in the Rim encountered the inherent problem of communication lag, and the colonies rapidly grew to separate from the founding country, while still maintaining relations with it.