Drum Law is a system, consisting of Diagrams, laws, rules, methods, their relationships and meanings. It is the content of the theory “Am Duong Ngu Hanh (ADNH)” or “Yin Yang Five Elements”, one of the most ancient philosophies of mankind.
Drum’s Law has existed in parallel with “I Ching”, one of the 5 Chinese classics since at least more than 2000 years ago but almost no one knows because it was not until 1893 that the drum was discovered.
Compared to the I Ching, Drum’s Law is both similar & different. If left alone, Ha Thu is similar to Ha Do & BQLD is the same as TTBQ of the “I Ching”. However, when we incorporate one or more other elements, for example Am Duong or Yin Yang of the Trigrams or/and the Trigrams’ number, there is no longer any exactly the same diagram.

Drum’s law of changes is characterized by 3 most outstanding features: originality, comprehensiveness & coherence.
The Originality of the Drum is the most noticeable feature. The drum was completed sometime between 900 BC and 200 AD, and was only discovered in 1893, after thousands of years buried deep underground. Currently the Drum is displayed at the National Museum of History in Hanoi1Source: Vietnam National Museum of History.
Its coherence manifests in the consistent & systematic connections & dependencies between the diagrams, laws, methods, their meanings, and the core philosophy & ideas of the Am Duong Ngu Hanh or Yin Yang Five Elements Theory.
The comprehensiveness is shown by the fact that the Drum has full set of the diagrams covering all 3 parts or interactions of Thien, Dia & Nhan or Heaven, Earth & Human. “Bat Quai Tai Nhan” or Human 8 trigrams is a guide or action plan to achieve the Great harmony, often referred to as the Bipolar Unity i.e. harmonizing, balancing and uniting Am Duong or Yin Yang, symbolizing all antagonists, differences & contradictions but correlating, mutual, transforming and complementing each other.
When decoding the Drum, we need to bear in mind the following points.

Drum is a work of art. For a work of art, the visible is just the tip of what is expressed, evoking something deeper hidden between images.
Drum is also the encoded book of changes. Ha DoHà Thư, đồ hình đầu tiên và nền tảng của Dịch Trống. Hà Thư phối với BQHT. Hà thư giống Hà đồ của Kinh Dịch.... More, 8 trigrams, 64 hexagrams were known for thousands of years before Drum’s creation, as early as 900 BCE. Therefore, on a circular surface of just 79.3 cm in diameter, it would not be a must to depict what is known unless it relates to the esoteric knowledge that the drum wants to encrypt.
Moreover, it is also unaesthetic and cannot be called encoding when Drum presented even an entire single diagram if it is an important & not yet known.
Law of changes is infinite, the more we understand, the more we’ll realize how little we know. We hope that the new findings will contribute to our collective effort to find and decode other mysteries of the Tao of changes and its foundation, the theory of “Am Duong Ngu Hanh” or “Yin Yang Five Elements”.