To answer both your posts. The biblical account is that soldiers guarded the tomb of Christ. But no matter who guarded it they had everything to lose if they permitted the theft of Jesus' bones.
Re: the bones of Buddha and mummies. Even cremation will not burn away all bone matter. Especially cremation not done in a commercial crematory. The cremains will contain bits of bone and of course there will be ash. So evidence of a body does remain. Also cremation was not a custom for body disposal in the ancient Middle East.
PS. I love the Mark Twain quote. Thanks for the laugh.
My favorite method of disposal of bodies is that of the Zoroasterians.
Their towers of silence exposed the bodies to carrion eating birds. Thus they would not contaminate any of the "four elements": Air,fire, earth or water.
My point was that the absence of a body does not prove presence of G-d.