User blog comment:Inept Wiki User/Cosmos in the Lostbelt: Post-Prologue, Pre-Anastasia Information & Speculation/@comment-34352073-20180405204219/@comment-1192086-20180407060751

I'm guessing that each lost belt diverged from the main timeline on the given date due to some perhaps world changing event, such as a new ice age occurring in 1570 for the 1st lost belt. The 2nd lost belt may be a result of Ragnarok occurring earlier than expected, thus Surtr ended up scorching the earth before appointed time. However, a percentage of humanity was protected by the gods due not wanting to lose their worshipers, but the gods' power began to wane if most of humanity gone. The 3rd lost belt may be the result of Qin Shi Huang achieving his desired immortality like you said, but his sanity eventually begins to wane due to his immortality. As result of his insanity he begins to fear that evil spirits are coming for him and wished to be protected at all times, so his mages animate the terracotta army by transferring the souls of actual soldiers into them. Then, with his particularly immortal army, he eventually conquered the world. Maybe for the 4th one someone was able to manipulate the Moon Cell to change the entire world, i don't know. The 5th one could be result of Sefar never coming to earth and thus the gods continued to rule over humanity. Now the sixth one is 500 AD, which is the date of the Battle of Badon Hill, King Arthur's twelfth battle, and in Fate is when Artoria fought and slew Vortigern. So maybe Vortigern was victorious in that battle and turned Britain into a hell like he wanted to, then Phantasmal Species spread from Britain to the rest of the world. Eventually though Vortigern gets crazy and decides to remove Rhongomyiad in order to reenact the Age of the Gods.