Dark

The Dark was the forty-year period between 40 Preflorian, 2134 OS and 0 Florian, 2174 OS when the Earth was uninhabitable because of the Comet Strike. While the planet was not literally 'dark', this was a time when humans had absolutely no inkling of what was going on topside, so spiritually it can be considered a dark time. It was broken by the Misunderstanding, when the humans nearly wiped out the machines but came to their senses and managed to open a dialogue with the machines, eventually leading to their return to the Earth's surface and the inauguration of the Florian Age.