(Herodotus, 'History.' IV, 93-6)
Zalmoxis (Saitnoxis) was the Supreme God of the Getae (or Dacians), a Thracian people inhabiting a territory including today's Rotnania, but also extending farther cast and northeast. Our only important information concerning this rather enigmatic deity is the text of Herodotus quoted below. The scholars have interpreted Zalmoxis as a Sky-god, a god of the dead, a Mystery-god, etc.
93. But before he came to the Ister, he first subdued the Getae, who pretend to be immortal. The Thracians of Salmydessus and of the country above the towns of Appolonia and Mesambria, who are called Cyrmaianae and Nipsaei, surrendered themselves unresisting to Darius; but the Getae, who are the bravest and most law-abiding of all Thracians, resisted with obstinacy, and were enslaved forthwith.
94. As to their claim to be immortal, this is how they show it: they believe that they do not die, but that he who perishes goes to the god Salmoxis of Gebelexis, as some of them call him. Once in every five years they choose by lot one of their people and send him as a messenger to Salmoxis, charged to tell of their needs; and this is their manner of sending: Three lances are held by men thereto appointed; others seize the messenger to Salmoxis by his hands and feet, and swing and hurl him aloft on to the spear-point. If he be killed by the cast, they believe that the gods regard them with favour; but if he be not killed, they blame the messenger himself, deeming him a bad man, and send another messenger in place of him whom they blame. It is while the man yet lives that they charge him with the message. Moreover when there is thunder and lightning these same Thracians shoot arrows skyward as a threat to the god, believing in no other god but their own.
95. For myself, I have been told by the Greeks who dwell beside the Hellespont and Pontus that this Salmoxis was a man who was once a slave in Samos, his master being Pythagoras, son of Mnesarchus; presently, after being freed and gaining great wealth, he returned to his own country. Now the Thracians were a meanly-living and simple witted folk, but this Salmoxis knew Ionian usages and a fuller way of life than the Thracian; for he had consorted with Greeks, and moreover with one of the greatest Greek teachers, Pythagoras; wherefore he made himself a hall, where he entertained and feasted the chief among his countrymen, and taught them that neither he nor his guests nor any of their descendants should ever die, but that they should go to a place where they would live for ever and have all good things. While he was doing as I have said and teaching this doctrine, he was all the while making him an underground chamber. When this was finished, he vanished from the sight of the Thracians, and descended into the underground chamber, where he lived for three years, the Thracians wishing him back and mourning him for dead; then in the fourth year he appeared to the Thracians, and thus they came to believe what Salmoxis had told them. Such is the Greek story about him.
96. For myself, I neither disbelieve nor fully believe the tale about Salmoxis and his underground chamber; but I think that he lived many years before Pythagoras; and whether there was a man called Salmoxis, or this be the name the Getae for a god of their country, I have done with him.