Roughly every thousand years, the
Shadows appear, causing
chaos
among the existing races, only to be pushed back to their homeworld by
the combined forces of the other races. The previous
Shadow War, which
occured around 1200-1300, resulted in their defeat at the hands of the
Minbari, under the command of
Valen, with help from the
Vorlons.
Conflict with Vorlons
The Shadows believe that the universe benefits from chaos and disorder,
allowing stronger races develop. The Vorlons prefer order.
The Shadows possess organic technology, and using living beings as the
cores to their vessels. Telepaths apparently have the ability to interfere
with the functioning of the core beings, effectively shutting down the
vessel.
Leaving the Galaxy
The Shadows left beyond the rim of the galaxy with Lorien after the conflict
in 2261.