The Arbryls are tree-people who evolved on a huge Eden-like planet containing only plant life. They are peaceful, slow-moving, and highly intelligent. They are unused to conflict and their philosophy is isolationist. They can usually be found standing perfectly motionless for huge amounts of time, thinking their tree-thoughts, pondering the world.
At times they conduct a planet-wide ritual, including every Arbryl, to tune their mystic energy vibrations to resonance. This ritual is exhausting and cathartic to them, and it restores the balance and calm they treasure.
As a side effect, their ritual of mystic resonance sends out a spherical ripple in space and time. This ripple expands hugely, distorting gravitational fields on an interstellar scale and causing star lanes to contract and close.
All Arbryls have agreed. It would be good to see other worlds. It would be good to learn about the universe.
Arbryls have no experience with the engineering needed to build space vessels, but they have incredible focus and concentration. An Arbryl can ponder the same question for years without cease. Many Arbryls have already anchored themselves and stand pondering the path to space.
System Isolators: The Arbryls can disrupt the flow of space. You can block all star lanes entering your colonized systems.