Lanke or Lankeshan (爛柯(山), Lànkē(shan), Lan-k'o (Shan); "(The Mountain of) the Rotten Axe Handle" in English), is a Chinese legend which has been compared to that of Rip Van Winkle, although it predates it by at least 1000 years.
The exact date of origin of the legend is unknown, but it has literary antecedents from the 5th century AD, and the "rotten axe handle" plot element was certainly present by an early 6th-century version.
One plot element of the legend features two immortals playing a board game, interpreted in later times as Go, so that Lanke (or Ranka in Japanese) has become a literary name for Go.