The Mayans ran out of rock. Get over it.
I just picture some really, really old Mayan who spent his life carving calendars into giant rocks finally getting too old one day and retiring and the chief asking if they should have someone else start and the old guy say, "I've got calendars going out for another 2,000 years. There's plenty of time to worry about that later. Hey, what are those funny ships out on the ocean?" And the rest is history and propaganda.