This doesn't really add much new but is a little too long for a comment. Credit to @Stiv and @Rand al'Thor for most of the leg work.
As was already pointed out by @Stiv, the puzzle refers to:
Lucian's True History
We see this because:
Lucian was a famous author from Samosata
The work in question is:
A famous piece of his which consists of fiction presented as truth, thus agreeing with the introduction to the puzzle.
In Section 44 of that work, we encounter the following:
There followed a sail through smooth water, and then a small island, easy of approach, and inhabited; its occupants were the Ox-heads, savage men with horns, after the fashion of our poets’ Minotaur. We landed and went in search of water and provisions, of which we were now in want. The water we found easily, but nothing else; we heard, however, not far off, a numerous lowing; supposing it to indicate a herd of cattle, we went a little way towards it, and came upon these men. They gave chase as soon as they saw us, and seized three of my comrades, the rest of us getting off to sea. We then armed — for we would not leave our friends unavenged — and in full force fell on the Ox-heads as they were dividing our slaughtered men’s flesh. Our combined shout put them to flight, and in the pursuit we killed about fifty, took two alive, and returned with our captives. We had found nothing to eat; the general opinion was for slaughtering the prisoners; but I refused to accede to this, and kept them in bonds till an embassy came from the Ox-heads to ransom them; so we understood the motions they made, and their tearful supplicatory lowings. The ransom consisted of a quantity of cheese, dried fish, onions, and four deer; these were three-footed, the two forefeet being joined into one. In exchange for all this we restored the prisoners, and after one day’s further stay departed. [emphases added]
Here we meet the:
Ox-heads who are presumably the horned cannibals of the OP's puzzle.
We also encounter in this passage:
If we take the part about the king being charged by a dozen deer at face value as a new detail invented by @Ichthys King occurring in the universe of the story (I can not find another reference to such an event in the rest of the work), then combining our insights with @Rand al'Thor's we see that there must have been a total of:
$12\times3\times2=72$ nails involved
As we have $12$ deer, each with $3$ feet, each foot with $2$ nails