Korean food is notoriously spicy, which is a bit out of place considering its cold climate and the fact that its neighbors in (northern) China and Japan don't eat nearly as much spicy food. Why and how did Korean cuisine specifically get so spicy?

Nobody knows for sure why Korean food is so spicy. The how is a bit clearer, and it turns out to be yet another side effect of the Colombian Exchange.

The introduction of the Mexican chili pepper (Capsicum annuum) in the seventeenth century was revolutionary for Korean cuisine, which does not seem to have been particularly spicier than North Chinese fare before the Early Modern period. Take kimchi, for example. The best-known kimchi we all know and love (to hate) is basically fermented cabbage spiced with pepper. But the broader sense of kimch'i is any fermented vegetable, and the spicy cabbage kimchi simply did not exist before the eighteenth century at the earliest. Among the earliest records of Korean kimch'i (Collected Works of Minister Yi of the Eastern Land, published in 1241) mentions the dish as "salt-fermented radish, a thing to last the winter."

Korea's first cookbook – Records for Mountain Houses – was written in 1459. It enumerates thirty-eight types of kimch'i, including such exotic dishes as fermented eggplant, fermented ginger, and fermented taro root, but few if any of them would be spicy in the way we imagine Korean cuisine to be. Korean sauerkraut would be a far better analogy than modern kimchi. At the time of the Records, Korean spices were principally black pepper, ginger, leeks, and Sichuan peppers, and even those were used rather sparingly.^1

Then, beginning in the seventeenth century, the chili pepper was introduced. It probably came from Europeans via Japan, and a 1614 encyclopedia already refers to chili pepper (which is variously called "Southern Barbarian plant" or "Japanese mustard"):

The Southern Barbarian Plant [Namman ch'o] is toxic. They mix it with soju [distilled liquor] in the taverns [to make the alcohol seem stronger] and those who died of drinking it are not few.

A little like the reception potatoes first had in Europe, the chili pepper seems to have been generally distrusted in Korea.

But over the course of the seventeenth century, and for disputed reasons, chili peppers became the condiment of choice throughout the Korean peninsula. The first mention of peppered kimch'i comes from Revised Farm Management, a 1766 agricultural manual that discusses how cucumbers should be stuffed with powdered pepper and fermented to make kimch'i. Management is also the first surviving text to discuss pepper paste and pepper powder, the two condiments by far the most responsible for Korean food being hot, in detail.

By the time Management was written, chili pepper appears to already have been a popular spice among both the elite and at least the urbanites of Seoul. In the Diaries of the Royal Secretariat (an account of court proceedings by the King of Korea's secretaries) entry for September 5, 1749, the king says:^2

Nowadays I am fond of pungent food, such as Sichuan peppers and chili paste.

And from the May 23, 1752 Diaries entry:^2

His Majesty said, "Pepper paste is something newly made in recent days, and had it existed earlier, I should certainly have eaten it then." [Kim] Sŏnhaeng [tutor of the Crown Prince] said, "And now the common people outside the palace gates are making it."

By the early nineteenth century, all records are clear that pepper is an extremely widespread condiment among all social classes in Korea.

The question is why, of course. One theory is that the Little Ice Age, a period of unusually cold weather, disrupted salt production. We do know that the Little Ice Age was devastating for Korea, resulting in major crop failures and famines in 1670-1671, 1695-1699, 1708, 1728-1729, 1731-1732, and 1750, each killing as many as several hundreds of thousands. The unusual climatic conditions might have been conducive for pepper, mistrusted as it was, to become popular as a replacement for salt before establishing an ever-growing niche in Korean cuisine in its own right.

Another point to note is that no other Colombian Exchange crop, except tobacco, has become as influential in Korea as chili peppers. But perhaps this isn't so surprising. While tobacco probably predated chili peppers, other American crops came much later and had much less opportunity to carve out a niche other than famine food. Corn is first mentioned in the aforementioned Revised Farm Management and probably arrived sometime in the eighteenth century, sweet potatoes came from Japan in 1763, and potatoes came from China in the 1820s.^3

^1 See "1400년대~1700년대 조선시대 고조리서에 등장한 향신료의 문헌적 고찰."

^2 To find the corresponding entries in the digitized Diaries of the Royal Secretariat, you need to search for Month Seven, Day Twenty-four of 1749 and Month Four, Day Ten of 1752 respectively, according to the East Asian lunisolar calendar. The two entries in question are all in Classical Chinese and have not been translated into either Korean or English.

^3 See 신편 한국사 (A New History of Korea) vol. 33 조선 후기의 경제 (The Economy of the Late Chosŏn), p. 43-45.