When Jou the Terrible ascended to the throne of the Shang dynasty (1600 - 1122 BCE), his behavior was so horrific that his name is synonymous with “a debauched tyrant.” Meanwhile, the nearby state of Zhou was gaining influence and the neighboring states would bring their disputes before King Wen of Zhou (1099 - 1050 BCE) to be settled since they knew King Wen provided a wise and fair arbitration.
On one of King Wen's visits to the Shang court, Jou the Terrible threw him in prison, where he was confined for seven years. While in prison, King Wen reflected on Yin and Yang, the Five Phases, and the trigrams of the Bagua. He decided to stack one trigram upon another trigram to form a hexagram--symbolizing a higher level of diversification. He attached a name and a description to each of the sixty-four possible hexagrams. He also rearranged the trigrams on the Bagua circle to reflect the complexity of the natural world--including the change of seasons and the interaction of the Five Phases. This arrangement is the post-heaven Bagua circle.