Terullian

The Terullians are a race of beings that existed circa the year 10,000. They existed outside of the Mutter's Spiral and were possibly in league with or had been conquered by the Sontaran Empire, which is suggested by the Sontarans using Terullian technology.

Technology
Terullians had developed a drive system for robots, one of which was used by the Sontaran Styre of the G3 Military Assessment Survey.

They had also developed a diode bypass transformer, which is used by Sontarans to feed on energy to recharge.