Who invented the lunar calendar?

This man is called Wannian. He invented the lunar calendar. One day, he went up the mountain to cut wood, because the sun was too hot, so he sat in the shade and rested. Suddenly, the movement of the shadow on the ground inspired him. After returning home, he spent several days and nights designing sundials. But in cloudy, rainy and foggy days, because there is no sun, the measurement will be affected. Later, the dripping spring on the cliff aroused his interest, and he began to make a five-story clepsydra. As time went on, he found that the length of the weather would repeat every 360 days.