Dragon Ball Z - episode 6 - 06 Jun, 1989

With Raditz defeated and Goku gone from this world, the surviving Z Warriors must begin preparing for the arrival of two more Saiyans who will reach Earth in one year's time. Piccolo takes Gohan into the wild for a severe training program, in the hope that his hidden power will be revealed. Meanwhile, Goku embarks on a new adventure in the next world, as he must travel the endless miles of Snake Way to receive training from the legendary King Kai! (Source: dbzepisode.org)