As grapes were never indigenous to Japan all grapevines had been introduced to the region with the movement of the spice route and silk roads over 2,000 years. It is believed that about 1,300 years ago grapevines were introduced to Japan where the climate was too hot, cold, wet – too extreme – to grow grapes for wine. Ultimately the existing grape variety most successfully grown in Japan became known as Koshu, which was the then name for the prefecture in which it grew. This prefecture then took the name of a Japanese prince and became Yamanashi, which remains the principal region producing Koshu. Responsible today for 40% of all Japanese grown wine grapes. Ampelographers continue to isolate the DNA of Koshu, but we do not actually know, outright, its source. What we do know is that it is a lurid pink on the vine, generally grown in the local tana method (overhead bamboo trellis).