The current Japanese flag was adopted on August 13, 1999. The symbol in the flag is the state emblem and has been the symbol of Japan for centuries. The Japanese flag initially became the country's national flag in 1868. The Japanese flag was modified slightly by new legislation in 1999. Legend says its origins lie in the days of Mongol invasions of Japan in the 13th century, when a Buddhist priest offered the sun disc flag to the Emperor of Japan, who was considered a descendant of the sun goddess Amaterasu.