It is my understanding that corn (maize) did not exist in the "Old World" until after being introduced from Latin America in the Colombian Exchange. Why then is it mentioned near the end of the "Oath of the Citizens of Chersonesos" (a Greek city state on the Crimean peninsula)?
Is this a mis-translation? What else could they possibly be referring to here? Was something the Greeks of this period regularly ate often referred to with a word that now also means corn?
"I will not give away corn to be removed from the plain, nor will I take it anywhere else away from the plain, except to Chersonesos. By Zeus and Gaia and Helios and the Virgin and the Olympian gods, if I abide by this oath, may it turn out well for myself and my family and my associates, but if I do not abide by it, may it turn out badly for myself and my family and my associates; may neither the land nor the sea bear fruit for me; may my women fail to bear any children . . . "
Corn in the classical meaning is simply a word for grains in general. In British use it's a synonym for grain, not for maize. It's related to German korn and dutch koren, which also both mean grain.
In older uses of the word it would sometimes be attached to other grain words to refer to the individual seeds. One might have a field of barley, but one would have a bushel of barleycorn.
In American English it pretty quickly attached itself to maize, and lost its general meaning as grain. That meaning has slowly been migrating out and it's increasingly replacing the general meaning in other English speaking countries.
You can find other examples if you look at other (especially older) British books. For example Genesis 42:3 in the King James translation of the Bible reads:
And Joseph's ten brethren went down to buy corn in Egypt.
Just to add a little Greek to the discussion (a little late unfortunately) the word is σῖτον, the accusative (object) form of σῖτος, which is the generic Greek word for "grain."
Incredibly generic, as this dictionary entry points out.