Convergence and Cataclysm
The Convergence wasn't a simple concept. As much as Ryu wanted it to be something that could just be explained in a few words so he would be less likely to leave any markers behind of his arrival here, by its very nature, it was very complex.
Still, after a few minutes, Ryu believed that he had come to understand the concept.
In the martial world in general, there were a whole host of matters that functioned based on a cyclical timeline. There were mysterious realms that only opened once every ten years, unclaimed Legacy Realms that might only open once every 100 years, Heavenly Paths that might only open once every a thousand years, and so on and so forth.