Recently, in addition to the Regency and Heian Japan research I've been conducting, I've started researching Joseon Korea. Though I spent two years living in South Korea, until recently my knowledge of pre-20th century Korea was somewhat limited. These entries will occupy my third slot in my rotating Thursday historical entry series. As of this time, I have no plan to add another period to my historical series.
Joseon (Joseonguk, lit. Joseon Country or Kingdom of Joseon) was the political entity that controlled the Korean peninsula from 1392 to 1897. At its height, Joseon controlled the entire area of what is now the Democratic People's Republic of Korea (North Korea) and the Republic of Korea (South Korea). Most of what we'd consider "Korean" culture today was established during this period.
The Joseon state was controlled by the Yi dynasty. The originator of the dynasty was one Yi Seong-gye, later Taejo. Throughout this series, I will be using the terms Yi Dynasty, Joseon, and Joseon Dynasty fairly interchangeably.
Originally Taejo was a military official under the previous Goryeo Dynasty (which, incidentally, also lasted 500 years). At the time Goryeo was dealing with being under the influence and presence of the Mongols, who had for several centuries prior also controlled China during the Yuan Dynasty period. The collapse of the Mongol-lead Yuan Dynasty and its replacement with the Han Chinese-lead Ming Dynasty provided an opportunity to eliminate Mongol influence. Goryeo military forces proceeded to eliminate Mongols remaining on the peninsula. Taejo made a name for himself during this period for actions against the Mongols, Japanese pirates, and certain Chinese forces, including an anti-Yuan rebel army.
The splintering dynastic transition lead to factions in the Goryeo court who supported both the Yuan and Ming Dynasties. Yi, as you might surmise from his blade dancing with the Mongols, was more of a Ming man. Unfortunately, the Ming also wanted Goryeo to cough up a large portion of their northern territory. I won't dive into the details of all the various claims, but the Goryeo government planned a further northern invasion into Ming territory. Yi was selected to lead the invasion despite his protests.
Instead, he turned around and overthrew the king. There were some shenigans with puppet rulers for a little bit but, in the end, Yi eventually ascended the throne himself inaugurating a new dynasty. Over the five centuries of Joseon's existence, the country reached heights of culture, technology, art, and literature. During this period, King Seijong the Great commissioned scholars to create hangul, the modern Korean alphabet, to improve literacy.
Joseon had a mostly peaceful two-century span between the the 17th and 19th centuries accompanying a mostly isolationist period. Unfortunately, that period of peace was book-ended by intense instability. The early centuries of the period were marked by intense and often violent political struggles between various political and scholar-bureaucrat factions.
Geography didn't help matters. The Korean Peninsula's position between China and the rising power of Japan lead to a battlefield destiny. Invasions from Manchus and Japan made the first three centuries of the dynasty an often unstable affair. Japanese and Chinese pirates also were a persistent problem.
Both the Kingdom of Joseon and the Yi Dynasty (effectively the same thing) would last until Japanese chicanery, including the brutal assassination of the reformist Empress Myeongseong, at the end of the 19th century and early 20th century robbed the Korean Peninsula of its independence until the end of World War II.