It is said that wasabi was first found growing in the wild by the Heike clan, which fled upriver to Mount Bahun after its defeat in the eighth century. Since many of this clan’s survivors originally came from nobility, they were familiar with the benefits of eating plants with their meat. They would therefore often make use of the plant to spice up their fish and venison.
Years later, a farmer began to cultivate it as a crop for the first time. This farmer then introduced his wares to a warlord by the name of Tokugawa Ieyasu. Ieyasu liked wasabi so much that he declared it a treasure and decreed that it should only be grown in the Skizuoka area.
As the popularity of wasabi grew, growers developed better cultivation practices to produce higher quality wasabi more efficiently. The secrets of some of these horticulture practices are carefully guarded by those few who use them. It is therefore that you can generally expect to pay high prices for authentic wasabi at Japanese restaurants.