In ancient times, the ancients divided the sky into four palaces, east, west, south, north and south, named after the Green Dragon (Canglong), the White Tiger, the Vermilion Bird, and the Xuanwu (a tortoise-shaped god). In fact, the sky was divided into four parts, and the seven major stars in each part were connected to form a line and named after their shapes. The Green Dragon is the god of the East, the White Tiger is the god of the West, the Vermilion Bird is the god of the South, and the Xuanwu is the god of the North.