This is called 'Talchum', and is one of Korea's traditional dances. It is performed wearing masks and singing. It's actually more than just a dance, the dancers are putting on a drama and each masked character is portraying a person, or animal, or a supernatural being. Some of these folk dramas reflect the antipathy and resentment felt by the common people towards nobility.
I love those colorful costumes and the workmanship that went into them and the masks, wow!
South Korea has some really beautiful and colorful stamps too. The colors of the stamps don't quite come across as well after being scanned, as they are on the card. They are much more vibrant.
