Based on several sources + the "Gaster entries" theory, etc.
Here's a very basic and rough UT timeline.
Might [and probably does] have mistakes but I mainly intended to clarify the strange jump in the timeline where things are seemingly "ancient times."
TL;DR on that is, the industrial revolution happened far later due to reliance on magic, a monster-led form of expression that fell out of style post-war.
happy zavok day. they told me i couldn't do it, that i couldn't make it in time. but i couldn't say no to making art of the GREATEST sonic character for such a SPECIAL day!