Legend has it that there was once a pair of girls who made alchemy in heaven. They fell in love with each other after accidentally eating the golden orchid elixir made by the other one. As punishment for violating the rules of heaven, they were turned into two cranes, one on the east side of the mountain and one on the west side of the mountain. They were never allowed to meet each other.
Every day when the sun rises, the crane in the east will chirp a few times, and when the sun sets, the other crane will chirp a few times in response, which means: I am here.
But the conversation between them is always separated by a mountain and the time from sunrise to sunset.