Known. A stone-blocked cave of burials was found inside a Maya city by the sea.
The city is Tulum, on the coast of Quintana Roo in Mexico. It was an important Maya place from the 1200s to the 1500s. The cave mouth, between two temples, had been closed with a large stone. Inside were burials, animal bones, and broken pottery from about 1200 to 1550 AD. A sea snail, fixed with stucco, decorated the front wall.
The page does not say what is still argued.
https://www.ancient-origins.net/news-history-archaeology/tulum-cave-burials-0020097