Before the invention of beds, my ancestors made a sleeping space out of bamboo plants. These plants are long hollow-like stem from the grass family poaceae. They harvested them and tied them vertically with ropes. They were said to be way more comfortable than they looked. In modern day, you can see exquisite beds and even fabrics made out of bamboo.
When I used to visit the village, my great grandma had her bed made out of mud. Mud in those days used to be carved into a very comfortable bedlike structure. Then they would have some feathers and furs over it to make it much more comfortable. These structures were used in place of the modern beds we are used to now.