Black Turtle‑Snake (Xuánwǔ / Genbu)

Two strands appear in the sources. Astronomically and geomantically, Xuánwǔ is one of the Four Symbols that partition the sky and seasons: the northern guardian associated with winter and composed of seven lunar mansions used in Chinese astronomy and astrology. In Taoist and popular legend tied to the cult figure Xuanwu, purification narratives describe expelled organs or washed‑out sins solidifying into a tortoise (stomach) and a snake (intestines) that terrorize the countryside until subdued by the returning deity; in some tellings the subdued animals are converted into the deity's attendants (the "Tortoise General" and "Snake General"). Both strands are attested in the provided materials as coexisting explanations for the compound's meaning and cult.

Iconographically the Black Turtle‑Snake is usually shown as a tortoise entwined with a snake. As a personified deity (Xuanwu/Genbu) it may appear in anthropomorphic religious depictions or literary narratives as a divine warrior who commands subordinate personified agents labelled Tortoise General and Snake General. The written name 玄武 does not literally name the animals; the characters connote "dark/mysterious" (玄) and a martial/warrior sense (武), while the tortoise+snake image expresses the compound's composite symbolic functions.

Primarily a protective and ordering force: it governs the north and winter quarter in the Four Symbols schema, contains seven lunar mansions used in astrological calculations, and carries watery/underworld affinities in Chinese star lore (a correspondence with Cetus is noted). In civic and ritual life it functions as a tutelary protector — invoked in palace north gates (e.g., Sinmumun at Gyeongbokgung), temple cult (Xuanwu temples such as those on Wudang Mountains), and funerary architecture (turtle‑shaped tombs in some Min customs) to secure places and the dead. Legendary narratives attribute agency: in purification tales the tortoise and snake formed from expelled impurities terrorize people until subdued and transformed into obedient generals under Xuanwu, indicating a mythic motif of subdual and rehabilitation by divine authority.