What is the extent of the power of the Dragon Balls?
You misunderstood Shenlong's words. Shenlong was created by the guardian of the Earth, Kami, in chapter 165. Therefore, Shenlong could not have greater powers than his creator. Shenlong's powers are not limited to the Earth nor are they limited to Earthlings. That's not how it works and it is not what he meant by that. They are disallowed from killing others, creating love, or anything that Kami wouldn't have been able to do with his own power.



Although the above statement is still rather vague. I mean, does this imply that they could wish for weak Earthlings to die, because Kami has the powers to do so? Or could Kami himself grant immortality, since his powers should be greater than or equal to those of Shenlong's? Those rules aren't ever explained in detail in the manga as far as I know, and it is never explained whether Shenlong can't kill anyone or only those stronger than Kami, but it is clear that Shenlong couldn't kill Nappa, Vegeta or any other villain Earth has encountered, because neither Kami nor Dende were that strong to begin with.

Dragon Ball wiki page

You can read more about the Dragon Balls' or Shenlong's powers on the wiki page.


  The Earth Dragon Balls are about 7.5 cm (approximately 3 in) in diameter, and they summon a dragon named Shenron. They were created by Kami, and later re-created by Dende. Shenron can grant a wish within its powers as long as it does not kill, create love, repeat a wish he previously granted, surpasses its creator's power, and a few more restrictions. Legitimate wishes include eternal youth, immortality, bringing back a scorched forest or even an annihilated planet. Also, it is possible to return a person to life, although only if they meet certain criteria, like dying of unnatural causes or within the time-frame of a year (half a century according to the Ocean Dub), and each individual can only be brought back once. The Eternal Dragon will grant the first wish uttered after it was called, by whomever is present.