Z'ha'dum is the place where the hero falls to his death and is resurrected, only to leave for the distant land with the elder races at the end of his journey.
Which come to think of it was also exactly what happened to Sisko in the fire caves at the end of DS9.
Which just goes to show how much these are simply archetypal story concepts that recur over and over throughout literature, as the post quoted by Jan stated.
The same things happen in Babylon 5
, in Deep Space Nine
, in Doctor Who, in Lord of the Rings
, in Star Wars
, in Greek/Roman mythology... hell, in the Bible. Where do you think the idea of dying, staying dead for a while, then coming back to life and going off to heaven comes from? It's all the same, and has been for millenia, which is why focusing this entire argument on two TV shows from the 1990s is just a little bit ridiculous.