Tsushiman language

The Tsushiman Language (Tsushiman: _) is a Austronesian language spoken in the Republic of Tsushima as the official language. While ultimately deriving from Proto-Austronesian, it exerts heavy influence from Chinese, Japanese, Korean, and Dutch.

Old Tsushiman
Around the sixth century, the island was conquered by Japan and was placed under the Ritsuryo System. The government attempted to enforce the use of Japanese, but failed to do so fully due to their weakening power; Classical Tsushiman thus developed into Old Tsushiman, exhibiting many loanwords and other influences.

Middle Tsushiman
Following the Mongol Invasion of Tsushima and Jeju and the adoption of many features from Middle Mongol, Old Tsushiman transition into Middle Tsushiman. This time period saw the rise of the Wokou as rulers of the island and thus the language strayed from Japanese once more. Following the Conquest of Jeju, Koreanic influence returned, but this time from the local dialects (which would eventually become the Jeju language). In addition, a campaign to increase literacy by (insert king here) led to the adoption of hiragana for transcribing the language.

Early Modern Tsushiman
In the early seventeenth century, Dutch traders overthrew the monopolistic Wokou government of Tsushima and established Dutch Cathay as their main trading base in East Asia. While Dutch was not directly enforced, it was considered the prestige language, and people attempted to emulate their speech. Thus Early Modern Tsushiman was born, which would also see a massive boom in literature and the overall progress of the islands. After the Meiji Restoration, the islands were returned to Japan, who began attempts to "reintegrate" the islands and their culture. However, due to Western pressure, this ended up failing at first. It was only until 1920 that the Japanese language was fully enforced, and even then heavy local resistance - including during the Second World War - prevented the widespread adoption of Japanese.

Tsushiman today
Post-war, the Republic of Tsushima was established, who in turn created the Tsushiman Language Society to promote the education, preservation, and standardization of Tsushiman. The modern Tsushiman language as we know it is thus a mixture of Chinese, Korean, Japanese, and Dutch.

Phonology
Tsushiman has an extremely complex phonology, with many rules governing how it works.