The Kulan were a humanoid race who invaded Earth in 2001. They usually invaded a planet by sending the Kulan Advance Evaluation Squad, detached from their main invasion fleet, to see whether the planet was appropriate for invasion.
The Kulan had two hearts, purple blood and skin that was more translucent than that of humans. They also had sharper hearing, thicker skulls and were more durable than humans. The Kulan used mental power to control their ships and magnetic induction as a power source. (Escape Velocity)
The Kulan were ruled by a body called the Council of Three. (Escape Velocity)
A Kulan Advance Evaluation Squad was sent to Earth either in 1997 or in 1998 but wasn’t heard from for nearly three years.
A Kulan invasion force once attacked a Chelonian colony, but were repelled.
In 2001 a Kulan invasion fleet was sent to Earth in order to invade the planet. Their plans were halted when the Eighth Doctor destroyed their fleet, killing the entire invasion force. (Escape Velocity)