What is the importance of the Korean peninsula?
It's importance is that they have been fighting there. It was also called some names because of a skirmish there.
How did the relative location of the Korean peninsula influence the development of Korean civilization?
Korean Peninsula Territory: Ko-Chosun ( Korean and Manchuria territory) Korguryo ( Korean and Manchuria territory) Parhae ( Korean, Manchuria, Siberia territory) Koryo-Kando ( Korean, Manchuria territory). Chosun Dynasty: China, Mongol, Japan, Russia, USA ( All five nations) wanted Korean peninsula for political and economic reasons. ( Geographical locations and natural resources etc). Korea Modern time: Korean political geography, Korean political and economic geography is shaped by Korean past, present and future history.
-- "The Yellow Sea" In response to the previous answer, the Yellow Sea separates The Korean Peninsula and Mainland China. The 'Sea of Japan' separates Japan from the Asian mainland (including the Korean Peninsula). The 'Korean Strait' also separates the southern coast of South Korea from Japan. Please see a labelled map in the related links below.