Conversation so far:
Were there any explorers in the Mayan region during this time?
CANNOTANSWER.
What was a notable event during this time period?
The Maya civilization developed within the Mesoamerican cultural area, which covers a region that spreads from northern Mexico southwards into Central America.
What were the origins of the Mayan culture?
By 6000 BC, the early inhabitants of Mesoamerica were experimenting with the domestication of plants, a process that eventually led to the establishment of sedentary agricultural societies.
Which crops did they raise?
The diverse climate allowed for wide variation in available crops, but all regions of Mesoamerica cultivated the base crops of maize, beans, and squashes.
When was the Mayan Calendar developed?
CANNOTANSWER.

Question: What else did they develop during this time?
Self-contained rewrite: What else in addition to the calendar did the Mayans develop during the Postclassic period??