Romulan Star Empire
From FEInfobase
The Romulan Star Empire was the governing body for the Romulan people. Like the Klingon Empire the Star Empire’s territory was based solely in the Beta Quadrant. By 2387 the Borg had already attacked the Romulans on a number of occasions and forced the Romulans to retreat from their homeworld of Romulus.
A fleet of nearly six hundred vessels were in range and able to defend Romulus in time. When the battle seemed to be hopeless a few ships stayed behind as the Romulan Senate among many other people in a fleet of about two hundred and thirty ships fled from Romulus and eventually out of Romulan space.
The Romulan Senate, or at least what was left of it, reluctantly agreed to join the Federation as they took refuge on Earth.