Gengetsutani (三日月月谷; Crescent Moon Valley) is the land of dragons, and thus is the place where all the dragons (at least in the samurai world) live. It is the residing place for all dragons, including ones of different natures. Gengetsutani is a majestically beautiful land, whose ultimate authority seems to be a council of dragons known as the High Dragon Lords. Even Dokuritsu Shitaryū, the ally of the Kodenbushi Yugara Yamamoto, heralded from this land.
It is almost impossible for a human to travel to Gengetsutani, as not only is the location is unknown to all but a few, but those knowing it are forbidden to speak it. Statements from Dokuritsu Shitaryū suggest that no human has ever knowledgeably located Gengetsutani. Gengetsutani is, however, impossible access by foot, for some unknown reason. However, it is known that Gengetsutani's location is extremely high, as Enishi mentioned that the valley was "touching the stars". When Enishi Musashi discovered Gengetsutani, he did so after falling from the highest reaches of the sky, and being projected afar, hence, "discovering" it via fluke.
Some of the inhabitants of Gengetsutani can use tenpurudō, to manipulate the ambient life-force in the world. There is a unique pool in Gengetsutani that holds a spectacular water immensely rich with raw Kousennoki, that infuses those who immerse themselves in it to attune forcibly themselves with Kousennoki. However, this water is considered so sacred, even the dragons cannot so much as touch it without the approval of the High Dragon Lords.