The He Tu, or River Diagram, is a sequence of numbers that is of significance in fung shui and astrological calculations. Unfortunately, although it is often mentioned in English fung shui books, there is rarely an elaboration on its practical significance; and as a result it is much misunderstood. The legend that states King Fuxi was the first one to see the He Tu, when it appeared on the back of a dragon horse emerging from the Yellow River, adds to the confusion.

Essentially, the River Diagram is an arrangement of numbers corresponding to the centre and four cardinal directions. Traditional Chinese books place north at the bottom of the page and south at the top. East is thus represented on the left and west on the right. Western readers will therefore need to adjust their bearings when reading fung shui texts.

In the diagram, the numbers one and six are at the bottom, signifying north and the water element. Four and nine are at the top, representing the south and fire. East and wood are represented by the numbers three and eight, while two and seven indicate the west and metal. The centre and the earth element are shown by the numbers five and 10.