In ancient Japan, there were essentially two different types of houses. The first was what is known as a pit-dwelling house, in which columns are inserted into a big hole dug in the ground and then surrounded by grass. The second was built with the floor raised above the ground. The style of house with an elevated floor is said to have come to Japan from Southeast Asia, and this type of building was apparently used to store grain and other foods so that they wouldn't spoil from heat and humidity.
- See more at: http://www.interior-idea.com/japan-home1.html#sthash.Uk06qyah.dpuf