to sit directly on the ground or floor, often used as an idiom describing a casual or informal seating arrangement; literally refers to the ancient practice of spreading a mat on the ground to sit on

To use the sky as a curtain and the earth as a mat; to live or sleep outdoors

To sit or sleep on the bare ground with the sky as one's roof; describes living in the open air or having a broad-minded and unconventional personality.

(idiom) to sleep on the bare ground