Korea is a large peninsula jutting into the Yellow Sea from the Asian mainland. Buddhism was introduced into the area during the 4th century and went on to become a major influence on Korean life, although it was persecuted after 1170 and disestablished in the 15th century in favour of Confucianism. By the 19th century, Buddhism's presence was minimal and further weakened by the Japanese colonial administration’s efforts to destroy it by forcing monks and nuns to marry.