For whatever reason, this became conflated with the Antique story of Ninus’ conquest of Zoroaster. As Abraham Valentine Williams Jackson discussed in his study of ancient sources on Zoroaster’s life, Eusebius indicates that the two were contemporaries in Praeparatio Evangelica 10.9.10: “in his (Ninus’) time Zoroastres the Magian reigned over the Bactrians.” Paulus Orosius, a contemporary of Augustine, in his History against the Pagans 1.4.3 had it that Ninus was the killer of Zoroaster, king of Bactria. Augustine said in City of God 21.14 that Ninus conquered Zoroaster. Isidore of Seville follows suit in Etymologies 8.9 and in his Chronicle. The whole sorry mess derives from a misreading of Ctesias, who wrote that Ninus battled Oxyartes (Diodorus, Library 2.6), which was misread as Xaortes or Zaortes. Thus Justin, in his epitome of Trogus, said that Zoroaster, inventor of magic, had a war with Ninus in which Ninus killed him (1.1.9-10), as did Arnobius a century later in the Adversus Gentes 1.5, speaking of “a war between the Assyrians and Bactrians, under the leadership of Ninus and Zoroaster respectively.”
As should be clear, the mistaken Late Antique identification of Ham with Zoroaster led to the transfer of the Pillars of Wisdom from Ham to Zoroaster, now a king of ancient Iran. But who first multiplied the pillars to fourteen I know not… It may be lost to history.
One thing that is not, however, is one of the most popular forms of the story, given in the Ovide moralisé 1.2405-2423 (composed c. 1317-1328), a 72,000-line Christian retelling of Ovid’s Metamorphoses, and to the best of my knowledge never translated from Old French into English. In this passage, the author has moved the whole event before the Flood and recombined Zoroaster’s fourteen pillars with the standard two pillars (of marble and brick) described by Flavius Josephus. I give here the lines, in which I have tried to give the sense of meaning rather than always follow the poetical form:
Cham made seven pillars of marble
And seven of brick, on which he wrote
The seven sciences which he possessed.
He did this because he knew
That there would twice come a time
When the earth would be destroyed,
Once by water and once by flame. He did not want
That the sciences should perish,
And so, in order that they would not perish,
On marble, which would not dissolve,
No matter how long it was submerged underwater,
And for fear of the coming judgment,
He inscribed the seven liberal arts and sciences.
And he inscribed them in brick — because the flames would
Only make the arts more solid
The drier and harder they became --
In order to preserve their memory.
This Cham, of whom this history speaks,
Is called Zoroaster.