In Japan, we associated with "rice" now from the close in the Jomon period, about 3,000 years ago.
When rice was transmitted from China, the meal of Japan changed from hunting collection to farming. And then, rice crop generalized after the Yayoi period, approximately 2,000 years ago, and food culture begins to develop mainly on rice.
From those days, rice was precious food and was money. Exchanging production capacity of rice and measured land, and rice was value similar to present money in Japan. We have worked hard to raise amount of production of rice.