Think of a gate that the sun has to go through every time it revolves around in the sky (this is ancient China's sun). Someone at the gate checks the time, and makes sure the interval is correct, then waves it through the gate for another pass, where it creates its next interval of time.
This method of keeping track of intervals of time was invented by the great Khans of Mongolia, specifically the most famous Khan of all: Genghis Khan (かん).
Genghis Khan has had a huge impact on the world as we know it, especially the Eurasian continent of the past, so he's going to come up a lot from now on. Be prepared to get very familiar with him and his friends!