Shui yue dong tian (2003)

In about 300 A.D., China is at peace after a lengthy period of civil war. The brilliantly gifted members of the Tong clan served the Empire until betrayed by an ambitious, half-mad relative. For 500 years the clan have lived in a secret valley, concealed from the rest of the world, and have become legend; few now believe they exist. The young heirs to the Tong clan leadership dare to leave the valley in search of a healing charm kept by a noble house. They find a world greatly changed in some ways, and in others the same as ever -- their ancient enemy still lives!