The 24 Directions (or 24 Mountains) is is an ancient Chinese geomantic (feng shui compass) concept used determine spatial orientations. It integrates principles from Chinese geography and astrology to guide architectural design, site selection, and other spatial arrangements.

二十四方位 24 Directions

卦四天干八地支十二共為二十四方位隂陽家名二十四山言山則向在其中如子山則必午向午山則必子向壬山則必丙向丙山則必壬向之類是也八卦惟用四隅而不用四正者以四正卦正當地支子午卯酉之位故不用卦而用支用支即用卦也八卦既定四正則以八干輔之甲乙夾震丙丁夾離庚辛夾兌壬癸夾坎四隅則以八支輔之戌亥夾乾丑寅夾艮辰巳夾巽未申夾坤合四維八干十二支共二十四天干不用戊己者戊己為中央土無定位也以二十四山分屬八卦則一卦筦三山戌乾亥屬乾壬子癸屬坎丑艮寅屬艮甲卯乙屬震辰巽巳屬巽丙午丁屬離未坤申屬坤庚酉辛屬兌謂之八宫以二十四山分屬五行諸家不同具各有義

二十四山 _Mount	八卦 _Trigram
^M23壬	坎☵₁₀₁
^M00子	坎☵₁₀₁
^M01癸	坎☵₁₀₁
^M02丑	艮☶₁₁₀
^M03艮	艮☶₁₁₀
^M04寅	艮☶₁₁₀
^M05甲	震☳₀₁₁
^M06卯	震☳₀₁₁
^M07乙	震☳₀₁₁
^M08辰	巽☴₁₀₀
^M09巽	巽☴₁₀₀
^M10巳	巽☴₁₀₀
^M11丙	離☲₀₁₀
^M12午	離☲₀₁₀
^M13丁	離☲₀₁₀
^M14未	坤☷₁₁₁
^M15坤	坤☷₁₁₁
^M16申	坤☷₁₁₁
^M17庚	兌☱₀₀₁
^M18酉	兌☱₀₀₁
^M19辛	兌☱₀₀₁
^M20戌	乾☰₀₀₀
^M21乾	乾☰₀₀₀
^M22亥	乾☰₀₀₀

4 TRIGRAMS, 8 HEAVENLY-STEMS and 12 EARTHLY BRANCHES form a total of 24 directions. The Yin-Yang practitioners call these the 24-MOUNTAINS. The term MOUNTAIN implies that its ORIENTATION is included within it. For example, if ^B0子_NORTH MOUNTAIN, it must correspond to the ^B6午_SOUTH ORIENTATION, if ^B6午_SOUTH MOUNTAIN, it must correspond to the ^B0子_NORTH ORIENTATION. Similarly, the if ^S8壬_⊕WATER MOUNTAIN, it must correspond to the ^S2丙_⊕FIRE ORIENTATION, if ^S2丙_⊕FIRE MOUNTAIN it must correspond to the ^S8壬_⊕WATER ORIENTATION. This pattern applies consistently.

Among the EIGHT-TRIGRAMS, only the four corner directions are used, while the four cardinal directions are not. This is because the four cardinal TRIGRAMS align directly with the EARTHLY-BRANCHES at the positions of ^B0子_NORTH, ^B6午_SOUTH, ^B3卯_EAST, and ^B9酉_WEST. Therefore, instead of using the TRIGRAMS for the cardinal directions, the EARTHLY-BRANCHES are used. However, using the EARTHLY-BRANCHES inherently involves using the TRIGRAMS.

Once the EIGHT-TRIGRAMS are established, the four cardinal directions are supplemented by the eight HEAVENLY-STEMS. ^S0甲_⊕WOOD and ^S1乙_⊖WOOD flank ☳_THUNDER, ^S2丙_⊕FIRE and ^S3丁_⊖FIRE flank ☲_FIRE, ^S6庚_⊕METAL and ^S7辛_⊖METAL flank ☱_LAKE, ^S8壬_⊕WATER and ^S9癸_⊖WATER flank ☵_WATER, the four corner directions are supplemented by the eight EARTHLY-BRANCHES: ^BA戌_W30N and ^BB亥_N30W flank ☰_HEAVEN, ^B1丑_N30E and ^B2寅_E30N flank ☶_MOUNTAIN, ^B4辰_E30S and ^B5巳_S30E flank ☴_WIND, ^B7未_S30W and ^B8申_W30S flank ☷_EARTH.

Together, the four corner directions, eight HEAVENLY-STEMS, and twelve EARTHLY-BRANCHES form the 24 directions. The HEAVENLY-STEMS ^S4戊_⊕EARTH and ^S5己_⊖EARTH are not used because ^S4戊_⊕EARTH and ^S5己_⊖EARTH represent the central ㊏_EARTH element, which has no fixed position.

When the 24 MOUNTAINS are assigned to the EIGHT-TRIGRAMS, each TRIGRAMS governs three MOUNTAINS:

^BA戌_W30N, ☰_HEAVEN, and ^BB亥_N30W belong to ☰_HEAVEN
^S8壬_⊕WATER, ^B0子_NORTH, and ^S9癸_⊖WATER belong to ☵_WATER
^B1丑_N30E, ☶_MOUNTAIN, and ^B2寅_E30N belong to ☶_MOUNTAIN
^S0甲_⊕WOOD, ^B3卯_EAST, and ^S1乙_⊖WOOD belong to ☳_THUNDER
^B4辰_E30S, ☴_WIND, and ^B5巳_S30E belong to ☴_WIND
^S2丙_⊕FIRE, ^B6午_SOUTH, and ^S3丁_⊖FIRE belong to ☲_FIRE
^B7未_S30W, ☷_EARTH, and ^B8申_W30S belong to ☷_EARTH
^S6庚_⊕METAL, ^B9酉_WEST, and ^S7辛_⊖METAL belong to ☱_LAKE

This division is called the EIGHT-HALLS. The assignment of the 24 MOUNTAIN to the FIVE-PHASES varies among different schools, each with its own interpretations and justifications.