Фу Си
The most famous "longma" occurrences are connected with the mythical "Hetu" "Yellow River chart", which along with the "Luoshu" "Luo River writing; Lo Shu Square" are ancient magic square arrangements of the "Bagua" "8 Trigrams" and "Wuxing" "5 Phases". They are traditionally linked with prehistoric Chinese rulers, a "longma" revealed the "Hetu" to Fu Xi or Shun, and the shell of a "gui" "tortoise" revealed the "Luoshu" to Yu. "The Great Treatise" commentary to the "Yijing" explains.