Distillation techniques first emerged around 3000 BC, in the age of the Mesopotamian civilization. According to the writings of the philosopher Aristotle, techniques for distilling wine had already been established in the fourth century BC. Those methods later spread throughout Europe, India, Thailand and elsewhere, and after thousands of years, were finally transmitted to Japan sometime between the mid-14th century and the 15th century.

Distilling techniques encounter Japan's unique koji mold.
That "miracle" resulted in the shochu we know today.

Methods for producing distilled liquor using fermentation to produce alcohol were originally divided between Western cultures that used malt, and Eastern cultures that relied on mold. Japan falls into the latter category, but used a completely different variety of koji mold from other countries. This encounter between ancient Mesopotamian distilled liquors and Japan's own koji is the miracle from which shochu was born.

When distilling first came to Southern Kyushu, rice and buckwheat were the primary ingredients for shochu. Unfortunately, the earth of the Southern Kyushu region, covered with a layer of volcanic ash, was not well-suited to the cultivation of rice and buckwheat, but it was suited to cultivating sweet potatoes. Indigenous to Central and South America, the sweet potato made its way to Japan after more than 10 millennia. The route it took to get there remains unknown, but this fateful encounter between shochu and sweet potato was responsible for the sweet potato shochu now enjoyed throughout Japan.