Interstellar Exploration, especially by the Sephirotics, involves a number of progressive stages. The following is a common approach, but by no means the only one used
1. Powerful telescopes, usually those attached to the Argus array survey an area of space, noting areas of interest.
2. Expendable exploration swarms, with no deceleration capacity, do flybys of the not so interesting areas and report back standard system data and also if they find anything interesting the Array might have missed.
3. Probeships carrying ais and uploads visit and perform thorough surveys of interesting areas/systems. The Argus telescope array has a very high resolution but closer examination always reveals more information. These probeships often start to construct infrastructure within promising systems even before the arrival of colony ships.
4. Colonization vessels show up and begin setting up the necessities of life (power collectors, conversion breeder reactors, space habitats, etc.) In recent millennia these ships often use advanced propulsion systems, Conversion Drive or Displacement Drive, gifted or more usually loaned to the colonists in return for an interest in the new worlds.
5. Once the colonies are established, the archai who supplied the colony ship (or its drive systems) will often arrive a few centuries or millennia later with a wormhole link to the Sephirotic Empires; in other cases a completely different transapient faction will arrive to take control of the system. The pioneers who explore and colonise the so-called Lightspeed Frontier are very often assimilated into one or another of the Sephirotic Empires or Metaempires of the Terragen Sphere sooner or later.
But for unknown reasons some worlds and systems are never taken over; these independent worlds retain their own culture and decide their own destiny; these worlds are rarely connected to the wormhole networks, but are left isolated and alone to develop in their own way. Most commentators think this is yet another on-going experiment or deliberate strategy of the archailects, but this is not known for certain.