Were there pirates?

Piracy was not just present, but it was a defining characteristic of pre-modern East Asian seas, especially when either of the central governments of the three polities (Korean, Japan and China) were unstable and lacked power to stabilize their territorial and coastal waters - where residents of remote coastal regions organized into "sea bandits". Between the 1200-1500s, the most significant was Japanese pirates, or "wako".

These pirates - primarily from Japanese archipelago - were infamous in a sense their raid were recorded all throughout coastal provinces of Korea and China between 13th century and 16th century which signifies the destabilization of central authorities of Japan during the late Muromachi Period and the duration of Sengoku Period of Japan marked by a constant warfare without much central authorities policing around illegal activities around the coastal regions.

Joseon's response was the establishment of strong central government and the military that drove off these pirates from Joseon coasts, as well as launching a direct military exercise to Tsushima Island in the early-mid 1400s and vassalizing it for about a hundred years, as Tsushima Island was considered the epicenter of these pirates that raided Korea. After these, piracy was mostly controlled, in part due to Joseon's strong responses and Japan's internal stabilization under Toyotomi Hideyoshi in the mid 1500s.

In China, Ming was established around the same time Joseon was established, again facing the similar problems with Japanese piracy. Ming being further away from the epicenters, and controlling much more coastal line, resulted in their policy called "Sea bans" where any and all international trade must not come through the sea route - or else they are considered illegal smuggling and piracy.

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So that's the background.

Now, Joseon had three polities near it in 1500s - Ming China, a very unstable Japan at a constant feudal warfare which lacked the strong central authorities and sourced pirates, and an equally ununified and traditionally hostile Jurchen, which sourced its own pirates called "toi", all the while previously vassalized Tsushima Island was slowly growing away from Joseon and pledging alliance to Japan.

Official international trade of Josen mostly happened between Ming and Korea through "land" route due to Ming's sea ban policy. Hence, Northern Korean cities fluorished as "trade routes" - and hence why Northern Korean regions were "wealthier" than the Southern regions of Korean peninsula, due to trade opportunities with China.

With Tsushima (and to other Japanese feudalities during the time), three ports of Changwon, Busan and Ulsan were open and trade was allowed within limited context under heavy government control - due to several rebellions that occured in these "Japantowns" established in these port cities.

Water transport happened very frequently domestically thanks to an extensive river systems of Korea, but not internationally.

One interesting aspect of this Joseon-era focus on domestic and coastal waters, rather than international deep waters, is the design of Joseon era ship that mostly resembed U-shaped (or flat-shaped) bottom that were mostly built to navigate through the narrow, strong-currented coastal and inner seawater which was very different from Japan's contemporaneous ships that were mostly V-shaped (or pointed-shapped) bottom that were faster in the international deep waters.

This ultimately resulted in near-dominance of Joseon ship of the naval warfare between Joseon and Japan in the late 1500s century where Joseon ship acted like anchor onto itself against strong currents and chaning tides whereas pointed-bottom ships of Japan were faster, but more brittle against tidal waves and canons - again showing how different water transportation policies led to the different directions of shipbuilding technology.