A beautiful open star cluster, 444 LY from Sol, containing hundreds of stars, the Pleiades excited human interest as far back as bronze age Old Earth - if not earlier. During the Information and Interplanetary Ages, many religious cults and sects - chiefly Nuage, Postnuage, and Ufoist - incorporated the Pleiades (along with Orion, Sirius, Zeta Reticuli, and other stars and nebulae) into their mythology. It was inevitable then that the Pleiades would be the target of colonization, both by visionaries and religious types, and by megacorporations seeking to make money off this prime piece of real estate.
Whilst several Nuagist vessels were launched towards the Pleiades during the brief nanotech window, the first vessel to reach the system was the K4H Exploration Neumann Alcyone, which arrived in 2541 AT. Takicorb, SecureSpace, and IGMC soon followed. In fact, so many corporations were descending on the cluster that the Mutual Co-Development Treaty was amended, and the Pleiades Non Coercion Zone (PNCZ) was established in a treaty update on Merrion.
Cheap amat and increasingly reliable conversion drive enabled other groups to arrive as well; everything from neo- nuagists and cosmufologers to small family-clade property developers. The megacorps had already staked out the best systems and worlds, and profitable migration was occurring.
The balance of power shifted in 2842 when the heterosophist cyborg clade Electra Entity in the outer Merope Oort cloud achieved posthuman nanocyborg status, and began feeding subversion templates to any and all other Pleiades haloers who wanted them. Following their subversion of the entire Farview Merope Orbital Park administration, an expeditionary force removed them from the area, as well as swept the oort clouds for any other squatters. A number of atrocities seem to have occurred on the part of the local authorities, but details remain vague. Over the next few decades further outbreaks of hypermutational alifes and subverted madverts completely altered the region's local info- and nano-ecology. While these were later shown to be descendants of original templates planted by squatters centuries earlier in comet cores, and were easily dealt with, property values plummeted, and large numbers of neodolphins (and a smaller number of sperm whale provolves, non-aligned hyperturings and Inner Sphere investors) moved in to buy up the most lucrative asteroids and habitats.
Most of the colonies in this cluster became affiliated with the Taurus Nexus during this period. Following the break up of the Nexus, the cluster was annexed by the Conver Ambi, the Solar Dominion, the Conver Ambi (again), Metasoft, the Dominion (again), and a rogue ISO that enforced a regional civilization/memeticity known as Truddonism before transcending.
Finally during the early Empires period what was left of the Pleiades Non Coercion Zone (PNCZ) was incorporated as an Autonomous Protectorate - now simply called the Pleiades Volume - into the Communion of Worlds, while the rest (including those original settlers who had stayed) joined the Terragen Federation.
At present the Pleiades member worlds seem to be going through a sort of collective shift, reflecting the uncertainty in the current galactic period. New relationships are being forged with the Empledokcetics and the Orion Federation (the latter for some reason seems to hold religious significance for many Pleiadans, especially the nuage ones), and new wormhole links have recently been established with them. Some neighbouring powers fear this may usher in a destabilizing effect, and that either or both the Empledokcetics and the Orion Federation wish to use the Pleiades Volume to gain a foothold into the Inner Sphere. But the actual outcome still remains to be seen.