the origin of 천만에요
천만에요, if we set aside 에요-suffix of spoken polite form there will remain 천만 that is equal to chinese 千万。i am actually interested in tradition of using 천만에요(千万）to express "you are welcome" and implied meaning og this expression .

Question

the origin of  천만에요 
천만에요, if we set aside 에요-suffix of spoken polite form there will remain 천만 that is equal to chinese 千万。i am actually interested in tradition of using  천만에요(千万）to express "you are welcome" and implied meaning og this expression .

Answer

But we say that as the meaning of "Not at all." in spoken Korean, not as the meaning of "You're welcome." When we see foreign movies with Korean subtitle, it gets taken as the meaning of "You're welcome." You can see the origin from 千不當萬不當(千不当万不当 in simplified Chinese characters) 千 = 1000, 不 = not, 當 = proper/appropriate. This is how the Korean dictionary says about it.