according to the mythic account recounted in the samguk yusa, the gojoseon (old joseon) kingdom was founded in northern korea and southern manchuria in 2333 bce.
the gija joseon state was purportedly founded in 12th century bce. its existence and role has been controversial in the modern era, and seen as likely mythology. the first written historical record on gojoseon can be found from the early 7th century bce. the jin state was formed in southern korea by the 3rd century bce. in the 2nd century bce, gija joseon was replaced by wiman joseon, which fell to the han dynasty of china near the end of the century. this resulted in the fall of gojoseon and led to succeeding warring states, the proto–three kingdoms period that spanned the later iron age.
from the 1st century, goguryeo, baekje, and silla grew to control the peninsula and manchuria as the three kingdoms of korea (57 bce–668 ce), until unification by silla in 676. in 698, go of balhae established the kingdom of balhae (c.f. modern bohai sea) in old territories of goguryeo, which led to the north–south states period (698–926) of balhae and silla coexisting.
in the late 9th century, silla was divided into the later three kingdoms (892–936), which ended with the unification by wang geon's goryeo dynasty. meanwhile, balhae fell after invasions by the khitan liao dynasty and the refugees including the last crown prince emigrated to goryeo, where the crown prince was warmly welcomed and included into the ruling family by wang geon, thus unifying the two successor states of goguryeo. during the goryeo period, laws were codified, a civil service system was introduced, and culture influenced by buddhism flourished. however, mongol invasions in the 13th century brought goryeo under its influence until the mid-14th century.
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Specific Effects of World War 1:
WW1 caused the downfall of four monarchies: Germany, Turkey, Austria-Hungary and Russia. The war made people more open to other ideologies, such as the Bolsheviks that came to power in Russia and fascism that triumphed in Italy and even later in Germany.