An artistic bed design from the late 1700s. The English word bed has an interesting etymology that probably parallels the development of the form (Plato even refers to the "form of a bed" in his writings). Dating back as far as ancient Aryan bdodh meaning in Latin fodi "to dig out as in a dug out place" or lair, the word transforms from Old Teutonic badjo, to Old Norman beor, to Middle High German bette, to Middle Dutch bedde, and into Old English bedd and our modern English bed. Oxford English Dictionary
Think twice if you think "King size" bed concept was invented in the 20th Century.
In China, the "state" bed evolved from a simple elevated platform to an elaborate piece of furniture with enclosed sides and a simple cotton mattress.
The state bed in Europe united the bed platform and the hanging "tester" with glorious textiles.
The status of and owner's rank in society was ofetn determined in part by their bed. Expensive, exotic textiles hung from the tester or canopy creating a private portion of a great hall or room. The curtains also helped to eliminate draughts.
State bedrooms became the seat of government. This concept dates back to the ancient Assyrians and Babylonians.