24 Shan, , are twenty four directions, literally translated as 24 Mountains. They were given names of four Trigrams, eight Heavenly Stems and twelve Earthly Branches. Without names of trigrams Li, Kan, Zhen and Dui just only because Zi, Wu, Mao and You corresponds to Li, Kan, Zhen and Dui. Almanac only mentions 24 Shan or Mountains because the facing direction, Xiang , of a site is certainly opposite to the mountain. Each direction has its five-element. And it is known as Zheng Wu Xing, . Actually, each direction's five-element is based on its Trigram's, Stem's or Branch's five-element attribute.

Ren, Zi and Gui belong to trigram Kan;
Chou, Gen and Yin belong to Gen;
Jia, Mao and Yi belong to Zhen;
Chen, Xun and Si belong to Xun;
Bing, Wu and Ding belong to Li;
Wei, Kun and Shen belong to Kun;
Geng, You and Xin belong to Dui;
Xu, Qian and Hai belong to Qian.
These are known as Eight Palaces.

Ba Gua means Eight Trigrams. They are Dui, Gen, Kan, Kun, Li, Qian, Xun and Zhen. The arrangement of the eight Trigrams in Xian Tian Ba Gua chart and Hou Tian Ba Qua chart are different.
Di Zhi, , literally translated as Earthly Branch, includes Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu and Hai, totally 12 Branches.

Xi Ci Zhuan: "There are five numbers belong to Heaven; and five numbers belong to Earth; each one of numbers in five positions has its mate and correspond to another."
Shuo Gua Zhuan: "Three Heaven and two Earth, the other numbers came from these."
1 and 6 are Water, and reside in North; 2 and 7 are Fire, and reside in South; 3 and 8 are wood, and reside in East; 4 and 9 are Metal, and reside in West; 5 and 10 are Earth, and reside in Center.
Northern Water rears eastern Wood; eastern Wood rears southern Fire; southern Fire rears central Earth; central Earth rears western Metal; western Metal rears northern Water. This is the order of the Producing Cycle.
Hou Tian Ba Gua

Shuo Gua Zhuan: "Qian is Heaven, and hence has the appellation of father. Kun is Earth, and hence has the apellation of mother. Zhen shows a first application, resulting in getting its male, and hence is calle the eldest son. Xun shows a first application, resulting in getting its female, and hence is called the eldest daugther. Kan shows a second application, resulting in getting its male, and hence is called the middle son. Li shows a second application, resulting in getting its female, and hence is called the middle daughter. Gen shows a third application, resulting in getting its male, and hence is called the youngest son. Dui shows a third application, resulting in getting its female, and hence is called the youngest daughter."

Shuo Gua Zhuan: "God comes forth in Zhen, brings into full and equal action in Xun, they are manifested to one another in Li, the greatest service is done for god in Kun, he rejoices in Dui, he struggles in Qian, he is comforted and enters into the rest in Kan, and he completes in Gen."
Shuo Zi (Yong): "Qian, Kan, Gen and Zhen are Yang; Xun, Li, Kun and Dui are Yin."
Jiu Chou means nine numbers. It is Luo Shu, and also known as numbers of nine palaces.
In hypothesis, it is unable to express the course without the central "5", and it is unable to express directions without center.
Shen Shi Xuan Kong Xue: "The center of nine palaces is Tian Xin." Tian Xin, , literary translated as "Heaven Heart".
And, the "Center" is known as Huang Ji, , Grand Center.
In hypothesis, if the Ji did not move then all trigrams did not move; the movement of all trigrams is caused by the movement of Ji.
Xuan Kong called the procedure placing the number of Yun to the center as Li Ji, establishing center.
Luo Shu

The Water of 1 and 6 subdues the Fire of 2 and 7; the Fire of 2 and 7 subdues the Metal of 4 and 9; the Metal of 4 and 9 subdues the Wood of 3 and 8; the Wood of 3 and 8 subdues central Earth; central Earth subdues the Water of 1 and 6. This is the order of the Subduing Cycle.
Na Jia is the method to correlate Trigrams with Heavenly Stems, five elements, directions and further the phases of the moon. In generally, the correlation is shown as following table.

Yearly San Sha includes Jie Sha , Zia Sha and Sui Sha . Monthly San Sha includes Jie Sha, Zhe Sha and Yue Sha . It is advisable not to engage in renovations in San Sha direction. Please note that the calculation of the direction of San Sha is based on 12 Branches directions, not 24 Shen/Mountains.

Xi Ci Zhuan: "In the Yi there is Tai Ji, which produced the two elementary Forms. Two Forms produced the four emblematic Symbols, four Symbols produced the eight Trigrams."
Shuo Zi (Yong): "Qian 1; Dui 2; Li 3; Zhen 4; Xun 5; Kan 6; Gen 7; Kun 8. Qian, Dui, Li and Zheng are Yang. Xun, Kan, Gen and Kun are Yin. Qian and Dui are Tai Yang. Li and Zhen are Xiao Yin. Xun and Kan are Xiao Yang. Gen and Kun are Tai Yin."

Shuo Gua Zhuan: "Heaven and Earth received their determinate positions; mountains and collections of water interchanged their influences; thunder and wind excited each other the more; water and fire did each other no harm. Among these eight symbols there was a mutual communications."
Shao Zi (Yong): "Qian South, Kun north, Li East, Kan West, Dui resides South-east, Zhen resides North-east, Xun resides South-west, Gen resides North-west."
Xiang means the facing direction, the opposite side to the Shan (mountain) direction.
Yue Jian literary translated as Monthly Establishment. It meant that the establishment of months, or various Qi in every month, was followed and corresponded with the pointing direction of the handle of Big Dipper. The following simulation was produced with Home Planet, showing the phenomena in northern sky around 450 B.C.

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