As a TCM practitioner, i am involved on a regular base with Taiosm principles like Yin and Yang. The Pa kua is a fundamental part used in one of the 5 Chinese classical Chings, the I Ching the book of oracles.
Here it is clear that the Pa Kua is very old and has as well in TCM as Bon so its own history with nice examples.
What is very similar in both cultures is the turtle as the source of the Pa Kua.
Further interesting philosophy regarding Taoism would be the prime cause or the Wu Chi out of everything is originated.
That resembles very much the emptiness aspect known in Dzogchen etc.
BONPO TRIGRAM LEGENDS:
The origin of the Yi Ching trigrams is found in ancient culture of the Bon, the pre-Buddhist religion of Tibet. Ancient Bon texts explain the origin of the trigrams by means of a mythological tale of a golden turtle which represents the process of the formation of the world in eight stages:
• 1. The pure essence of the elements emerged from the mouth of the turtle as vapour and transformed into the 'old father of existence' (Sipa yab rgen ), the first and most ancient trigram, Khen, symbol of the sky. He is described as a old man with white hair, dressed in yellow silk, riding a dog and holding a crystal wand in his hand.
• 2. The impure aspects of the elements emerged as the dung of the turtle and fell and became 'old mother of existence', (Sipe yum rge ma) Khon, the second trigram that symbolises the earth. She is represented as an old lady with white hair the colour of a conch-shell, with a hundred wrinkles on her face, dressed in white silk, holding a hoe in her right hand and a wooden stick in her left and riding a sheep.
• 3. The old father and mother of existence married and from their union came the eldest son, the third trigram, Ghin, who symbolises the mountain connecting sky and earth. The eldest son is represented by a figure resembling a monk, holding a sacred book in his hands and riding a rose-coloured ox.
• 4. Then the wind blowing through the stony mountain valleys gave rise to the fourth trigram called Zon. This trigram is symbolised by the eldest daughter represented as a young woman dressed in yellow silk, riding a dzo, and holding in her hands a balloon-like round bag made of skin.
• 5. The action of the wind produced the fire element symbolised by the trigram Li which is represented by the youngest daughter of the old father and mother of existence. She is rosy in colour, with a horse's head, dressed in red silk, holding a ladle full of blood in her right hand and a torch in her left.
• 6. From the encounter of air and fire arose the sixth trigram called Kham which is symbolised by the grandson of the old father and mother and represented as a black-coloured man, with long hair, dressed in black, holding a leather ball full of water in his hand and riding a black pig.
• 7. Then from the interaction of the fire and wind arose the rain which fell thus originating the trigram Zin symbolised by the tree. The trigram Zin is represented by the grand-daughter who is greenish in colour, dressed in green silk, riding a green donkey, with her hands crossed on her chest and holding a plant.
• 8. Through the function of the element fire which melted the earth, its pure essence, metal (gold, silver, copper, etc.), manifests, associated with the trigram Da. The trigram Da is the youngest son of the old father and the old mother and he is represented by a young warrior wearing a helmet and armour, holding a sword and a lance in his hands and riding a goat.
Prof. Thubten Puntsok tells us:
"According to the tale, the trigrams Kham and Zin came about in this way. The elder son, Ghin wishing to find a bride, circled Mount Meru, the 'axis mundis' three times in a clockwise direction; Zon, with the same wish circled the ocean three times in a counter clockwise direction. The two of them met in the midst of a vortex of wind in the country called srin po gdudg pa can gyi yul, which means 'the country inhabited by wild cannibals', in a place called ye le dgung sngon or 'primordial sky'. In the midst of the vortex they did not recognise each other and engaged in an incestuous relationship. From their union was born a son, the trigram Kham, and a daughter, the trigram Zin.
This incestuous relationship was a tragedy that caused a disturbance among various classes of non-humans, in particular between the Devas and the Nagas, who became drunk with mental confusion (because existence had been defiled by the incestuous relationship) and coupled between themselves thus giving birth to the Eight Classes of demons and gods. Following this the beings of the six classes of existence were born, the hell beings etc., and illnesses and suffering arose among these classes.
This suffering which struck the inhabitants of the world came to the attention of the old father, the trigram Khen, who called out asking what was happening. A reply came from the sky saying that what was happening was the result of an incestuous rapport of the elder son with his sister and that it would be beneficial if the family did not remain together but split up to reside in the eight directions. Li, the younger daughter, with the wish to reconciliate the family, approached the old father, Khen, apologising for the misunderstanding between the two trigrams, Ghin and Zon. which had caused the suffering troubling the world. The old father, however, misunderstood her words, got angry and the problems within the family did not come to an end so the members of the family took up residence in the eight directions. Each one took his or her property to their direction and these belongings (including rocks, pieces of wood and so forth) were the very substances that, later on, became used in the rites to pacify the damage caused by an unfavourable combination of the elements or of the trigrams.
Finally the old mother, who was born in the earth sheep year, died at the age of 226 in the wood dragon year. She was buried in the earth the following year, that of the wood snake. At that time there was no funerary ritual to appease the Eight Classes and to balance the elements of the family, and, as a consequence, the old father who was born in the earth dog year and lived for 253 years, died the following year, the metal pig year. In a similar fashion, as the result of the lack of proper funerary rites, Zin, Zon and Kham suddenly died. After that Da, Li and Ghin discussed the matter and created the rite to appease the Eight Classes of demons and gods and to balance the elements within the family. As a result of this the world enjoyed peace and prosperity for many eons.
Following this period of prosperity, the world began to decline and all its inhabitants experienced an augmentation of mental affliction. At that time the Sage Yod po appeared who recounted the legend of the origin of the Parkha and became the first Tibetan to explain astrological calculations.
After many centuries in a period in which no form of writing existed, the teacher of astrology named Sa bdag nag po started to indicate the parkha, the mewa, and the animals with white and black pebbles.
After many centuries, the prince Shi kha then tse born (2551 BC.) in the year of the metal rabbit, established the rules of governing using astrological calculations. In 1957 BC in the wood monkey year, the astrology master Sa bdag rlung rgyal was born, who taught the sage nGnon po. On the basis of the instruction of his teacher, the latter elaborated a way of astrological calculation using the combination of the twelve animal signs with the five elements. He associated colours with the five elements: green for wood, red for fire, yellow for earth, white for metal and black for water and then associated these elements to the parkha and animal signs by way of different dots of colour.
In 1557 BC. in the year of wood mouse, another master of astrology, Ze'u kong 'phrul chung was born. He applied the mother-son-friend-enemy relationship to the field of medicine for the first time. In the wood mouse year in 1197 BC., a famous astrologer, Kongtse sphrul gyi rgyal po, was born. On the basis of his astrological knowledge and on the request of four of his most intelligent students he composed 357 treatises on the rituals of the gto, mdos, yas and the gljud, which have the function of balancing the elements and pacifying the disturbances caused by the Eight Classes of spirits and gods.
In 417 BC. in the wood mouse year, Nyatri Tsenpo, the first Tibetan king, was born. When he became king of Tibet, the so-called 'community of astrological practitioners' developed and propagated astrology widely. At that time, on the basis of the observations of the southerly and northerly movement of the sun, the observation of the stars and the migration of birds, the rain, clouds, wind and snow, the community prepared the solar calendar of 360 days mainly for the sake of the farmers and nomads.
There are many details regarding the development of the elements, how disturbances manifested and how substances were used to pacify the imbalance of the elements but we would need a week simply to explain them. This is a mythological story not a real one, nonetheless its symbols could be considered to be an invaluable field of research. This information concerning the mythological origin of the trigrams as well as the mewa or numbers can only be found in the Bon texts; one does not find similar explanation in the astrological treatises of China or other countries. In fact, when Chinese astrological experts are asked about the origin of the parka or trigrams they do not have a very clear explanation and sometimes refer to a particular race of people called Yi who lived on the border between China and who were originally Tibetans with customs and beliefs closely linked to the Bon culture."