Why did ancient Koreans wear white clothes?

Koreans love cleanliness and wear white clothes, saying that white symbolizes cleanliness and purity. Even weddings and funerals are not like red envelopes here, but white ones. In ancient times, whenever a great man died in court, the court ordered people to wear white clothes and linen for him, Dai Xiao. But for a while, the big shots in South Korea always hung up. (It's a tragedy) Ordinary people had to wear white clothes all the time, and later it became a custom.