The Feast (at least).

Then everyone who survives, of all the nations that have come against Jerusalem, will go up year after year to worship the King, the L-RD of hosts, and to celebrate Sukkot. Any of the families of earth that will not go up to Jerusalem to worship the King, the L-RD of hosts, will have no rain fall on their land. And if a family of Egypt does not go up to present themselves, on them no rain will fall and the L-RD will afflict them (and all the nations that do not go up to keep the festival) with a plague. This will be the punishment to Egypt, and all the nations which do not go up to celebrate the Feast of Booths.  Zechariah 14:16-19

What explanation will be given, and what else, if anything, will it take for the nations to finally understand that they are to obey G-d's instructions? Here, they've just finished (and failed at) their attempt to annihilate Israel, and now find themselves journeying to the New Jerusalem to present themselves before their newly (at last, visibly) enthroned King - the most astonishing, most ironic event of all time.