Like other classical cults, the religion of Dionysus was assimilative, incorporating pre-Hellenic elements into the traditions of the Indo-European migrants to the Greek lands. The viticultural aspects of the god must have originated with the cultivation of the vine, and as the religion spread to the Aegean from its eastern homeland, it assimilated deities and shamanic rites that involved magical plants in use before the advent of wine. In the final incorporation of the god into Greek religion, Dionysus became a son of Zeus and assimilated the migrants' own traditions of Asiatic shamanism. As a god who had now been born into the Olympian age, his gift of viticulture, like Demeter's cultivation of the grain, was indicative of the evolution toward superior Hellenic civilization and of the successful hybridization of cultivated plants from what were supposed to have been their wild forms in more primitive times. Primitivism, which was associated with the dead, was thought, however, to pose an atavistic threat to civilization if it were not accorded an honored role in the final Olympian settlement, and in terms of the Dionysian religion, the pre-viticultural aspects of the god were part of his total identity and had to be balanced in maenadic rites against other enactments that centered upon the god in his Olympian evolution. In the Bacchae, Euripides told the story of the god's advent from Asia Minor, where he has discovered the vine plant, to Thebes, the pre-viticultural kingdom where the first of his two births had taken place. Pentheus and the Theban women discount the claim of his Olympian birth and reject his gift of the newly discovered wine. Pentheus represents the primitive identity of the god and is presented in the play as having a temper that is the antithesis to the calming and pain-relieving effects of the cultivated intoxicant. Appropriately in his kingdom, only the wild identity of the god can function. By a reenactment of the two births, this primitive enemy of the god is consecrated for his role as sacrificial surrogate, whose violent death will vindicate the Olympian identity of Dionysus. Since Thebes has refused the assimilative evolution, the maenadic revel there is not a function of the god's totality, and atavistic forces undo the civilization that Cadmus had founded when he planted the first crop at Thebes and the whole kingdom, at the end of the play, reverts to primitivism. Such a reversion is the theme in other tragedies about Thebes, and traditionally the rejected pollution of that city is transmuted into a source of chthonic fertility for Athens, a city, unlike its neighbor, that has struck an eternal accord with its own primitive origins and has welcomed the god, as is obvious in its festivals of drama, where Dionysus functions in his higher aspect as a founder of culture.