- Kamado stove, Tokyo National Museum
A small cooking stove was introduced around the 5th century from the Asian continent. A pot was inserted into the hole at the top. It was placed against the wall so its flue would vent smoke through a hole in the wall to the outside. This feature greatly reduced indoor pollution and improved the quality of the air within the home.
The kamado stove improved air quality in the home (Kazuya Inaba & Shigenobu Nakayama)
The user fed fuel wood into the stove through the arched opening in front and heat rose beneath the pot. The user then placed the food to be cooked in a container that nestled in the round opening at the top of the stove. The kamado improved fuel efficiency and made it easier to control cooking heat.
- Miniature kamado from an ancient burial mound, Tokyo National Museum
Heritage of Japan 
wow it is a great inovation of its time but damn grateful that we do not have to use ites such as this any more. i think i will stick with my pots, pans and over.
Most interesting. Very simple good solution, very good for cold climate. Very simple to build and keep going! Appropriate technology.