Mercenarius
Banned
When were Korea's last chances for it to finally begin a modernization drive instead of further isolation?
Korea was in the beginning phases of modernization in the 1890s, and might have been able to remain independent if Russia had more power projection in the region.
Or a more successful China.
Korea was invaded by 14 countries throughout its history, although eight of them mostly targeted what is now Manchuria. As a result, the peninsula's population decreased over the long run from the 10th to 17th centuries, from a peak of around 8-12 million under Goryeo before the Mongol invasions, to around only 4-6 million soon after the same invasions, after which it stagnated (~6-8) until the mid-17th century. For comparison, based on data compiled by the Tang after it occupied Baekje and Goguryeo, the peninsula's population (excluding Goguryeo's former possessions within Manchuria) was probably around 7-9 million by the late 7th century, despite major population displacements due to war. However, the introduction of cash crops since the 16th century did cause the population to double or triple (12-18 million) by 1800 or so, although it then stagnated again around 15 million or so by the middle of the century. Each major war led to widespread destruction, forcing the country to rebuild over and over again, and made it extremely difficult to continuously pursue innovations over decades, if not centuries. As a result, while there were several major cities, the bulk of the urban population generally remained concentrated around Hanseong (Seoul), somewhat limiting developments.
On the other hand, the Japanese population continued to grow at a steady rate since the archipelago was politically consolidated around AD 500, when the population was around 4-5 million, after which it reached . . . 25 million by around 1800 or so. This gradual growth for over a millennia was possible because it never experienced major foreign invasions, and it was only briefly threatened, not directly invaded, by the Mongols in the late 13th century . . . Continued population growth . . . meant that although Edo (Tokyo) became prominent by 1600 or so under the Tokugawa, other major cities, such as Ōsaka, Kyōto, and Nagoya, also continued to flourish for over two centuries. These conditions ultimately allowed further developments and innovations to be compounded over time, due to a larger labor force mostly stemming from continuous levels of population growth.
In other words, in order for Korea to successfully pull off a "Meiji," it would first have to systematically carry out major land reforms with the aim of boosting population growth rates over the long term, which would essentially require a PoD around 1700-50 at the latest, as the court would need to enact favorable policies after systematic restructuring.
. . . While Japan did not have enough natural resources for Western powers to express significant interest in colonization, it was also strategically located near China, Southeast Asia, and various islands across the Pacific . . . Although implementation of Sakoku, beginning in 1633, sharply limited Nanban trade soon after, a continuous influx of Rangaku from the Dutch meant that the country would eventually be prepared to tackle further reforms soon after the US arrived in 1853 to open up its trading ports.
On the other hand, Korea was much more geographically isolated in comparison, which meant that although several shipwrecked sailors did temporarily visit the peninsula, they generally did not find anything interesting in particular, especially as the Imjin War and Manchu invasions had respectively left the peninsula devastated in the late 16th and early 17th centuries. France eventually sent several warships in 1866 because Joseon had executed several French missionaries, not because they specifically wanted to open up the peninsula for trade, and although the US also attacked Korea five years later with five warships, it was not until 1876 that the country was forcibly "opened up" to trade by Japan.
However, it's also important to note that both Japan and Korea had extensive trading contacts with China and the Ryukyus, and also traded with Southeast Asia through the latter, which would also have explained why both had been hesitant to trade more extensively with Western powers before technological considerations eventually came into play.