More specifically, the Mayans dated the (most recent) creation as happening on 13.0.0.0.0, with the next day being 0.0.0.0.1. Given that Mesoamerican cosmology explicitly talks of multiple incarnations of creation, some people took it to mean that the current cycle of creation would end on 13.0.0.0.0, but there's no evidence that any Mayan thought this was true.