as a common chinese nationalist, i feel so interesting when i see this three leg bird, because i know in chinese culture (lie), the 3-leg bird stand for the Sun, hehe , we chinese call it :三足乌！. just like what the pic want to tell to its audiance, so what can this imagine prove? it means that the culture of 高句丽 is or, at least, very close to chinese culture (hilarious) !
hehe , when i see these things, i can tell alot about 高句丽:) (lie)
