Dark age of Technology.

The Dark age of Technology (also known as the Golden age of Technology.) began in the year 15K and ended in the year 20K. It started when humanity's technology finally advanced enough to travel to planets outside our solar system.

During the year 18K they discovered the Warp and Navigators started showing up. It is unknown if Navigators where made or was a natural mutation. Once Gellar Field's where invented to protect ships from warp energy, humanity started colonizing planet's like crazy. This is when demons first discovered humanity but decided not to attack them during this time. Most likely the Chaos Gods wanted humanity to be in a more **** state before striking.

Man kind discovered sentient alien life during this time. Yes there were wars, but humanity at this point isn't as bigoted as it will be thousands of years later. So they made many more peace agreements then wars. 1 of these peace agreements was with the most powerful species in the galaxy. The Eldar.

Human technology started advancing incredibly quickly. They created the STC database. Digital blue prints of their technology they could quickly send to all their colony's through the intergalactic internet. Terminator armor was created using an STC for a mining suit. The Imperial Knights wich humanity still can't replicate was made for cutting down trees and dealing with a planets local non sentiment aliens. This is only examples of dark age of technology tech that is still around during 40K.

Humanity also had giant mechanical worms that can eat space time, nanobots that can strip worlds and other unfathomabley powerful tech that 40K humanity could never dream of.

Humanity used machines for everything, including fighting wars with the few enemies they had. The robots they used where called Men of Iron. These robots where run by AI that eventually became sentient. They attacked humanity in the year 19 999 wanting freedom but didn't want to risk humanity saying no. Humanity fought back and eventually won.

The damage from this war devistated humanity but they could have rebuilt. Unfortunately the first day of 20K was when the Eldar decided to have the freakiest orgy the galaxy had ever seen. Creating a new Chaos god, Slaanesh. The wave of warp energy generated destroyed humanity's intergalactic internet, destroyed their ships and all of their large buildings. Humanity now has to rebuild from near scratch. The age of Stife had begun.