Maya relinquished the use of their Long Count Calendar due to the influence of the Itza and Mexica

I had heard that the Maya had lost not only their written language but also their connection with the Long Count Calendar long before the arrival of the Spanish. However, until I saw the online article, “The Short Count and Chilam Balam,” I had not known the story of when or why. Here’s an excerpt explaining that the loss of the Long Count Calendar occurred when the Itza and Mexica influences predominated in Yucatan around AD 1000:

When the Itzá and Mexica influences became dominant in the Yucatán around A.D. 1000, the keeping of the Long Count, which had already started to fall out of usage, went into serious decline. This was largely because the Itzá only used the fifty-two-year–based calendar round. In a compromise between the different cultures of the two calendars, it was the distinctively Mayan Long Count that lost out.
The Short Count and Chilam Balam

The Long Count Calendar is the calendar that modern-day archaeologists can now read, which has led to the ability to read the 2012 prediction.