Goku met the Yardrat race when his Saiyan space pod crashed into their planet during his escape from Planet Namek, following Frieza’s defeat. The Yardrats are a short, pink-skinned and peaceful people who nursed Goku back to health.
The common technique known by the Yardrat race is the Instant Transmission ability that allows a person to instantly appear at whichever location they concentrate on that has a ki source. They taught this technique to Goku and even gave him an outfit worn by all the members of their people.
It can be assumed that since Goku's space pod, which belonged to the Ginyu Force, was auto targeted to the Yardrat planet, that they were the Ginyu forces next target. So its is lucky the Goku and Vegeta took out the Ginyu Force, or else the Yardratians would undoubtedly be eliminated.