The chronology of Suzerain's mortal realms is the same as the time line of the real world. Man evolved on Earth, settled into a hunter/gatherer existence, took up agriculture, learned to write, and history took over from prehistory. The great civilizations are still there - ancient Egypt, China, Greece, Rome, imperial Europe, the USA...
And then we get to 'now', the modern day. What happens next?
From the Suzerain perspective, all these historical ages of man's development are realms in the Timeline family of mortal realms. Timeline doesn't end there, though. It goes into the near future, working under the premise that scientists discover the existence of Pulse energy and develop Celestium. Shortly after, the Pulse War begins, nearly destroying all life on the planet.