As early as 2,500 years ago, about the Spring and Autumn Period (770-476 BC), China had determined the point of Winter Solstice by observing movements of the sun with a sundial. It is the earliest instituted in the 24 seasonal division points. The Northern hemisphere on this day experiences the shortest daytime and longest nighttime. After the Winter Solstice, days will become longer and longer. In some parts of Northern China, people drink dumpling soup on this day; while residents of some other places eat dumplings, saying doing so will keep them from frost in the upcoming winter. But in some parts of South China, the whole family will get together to have a meal made of red-bean and glutinous rice to drive away ghosts and other evil things.