From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
The Kashvar are a race of power hungry aliens.
The Kashvar appeared in Dragon Ball Z: Wrath of the Dragon. They set out to kill all other life other than their own. They were only seen when Tapion explained their origins. Hoi, the evil wizard who tricked the Z Warriors into releasing Tapion from his enchanted music box, was the last known member of this race to still be alive (according to him).
Not much is told about the Kashvar other than their belief that they were the dominant race in the universe. More than one thousand years before the events of Wrath of the Dragon, the Kashvar waged war upon the Konatsians on their homeworld of Planet Konats. Tapion explained that they used their evil magic and brought the evil Hirudegarn back to life and used the creature's awesome power to completely ravage the planet. Almost half of Konatsian's population had been killed off by the near end of the war.
It was not until an enchanted sword and two ocarinas were found that the tide turned. A powerful wizard and two brothers, Tapion and Minotia, used these items to successfully slay the beast. The wizard then sealed the two halves in each of the brothers. Specialized enchanted music boxes were created to hide the brothers from the Kashvar. Tapion and Minotia were then sealed and sent off into the far reaches of space where they drifted for over a thousand years until they were found by Hoi and brought to Planet Earth.
During the battle against Hirudegarn on Earth, Hoi was stepped on, which evidently killed him, bringing the Kashvar race to final extinction.