Krattorian

Krattorians were a race of blue-skinned, humanoid slave traders. One Krattorian ship, commanded by Kest, landed on Skaro to collect sand. All except Kest were killed by the Daleks, who then captured their slaves and their ship. Although the slaves later escaped in the ship, the Daleks had already learned from it the secrets of space travel.

The Daleks used the knowledge to begin their experiments in space travel. (COMIC: Power Play)