The Long Night is the name given to the Period of time between the Fall of the Commonwealth and the resurrection of it, spanning more than 300 hundred years. This stretch of chaos was made worse by the fact that nearly all of the planets who endured it had been at peace for over 1000 years and had not known such threats and hardships.
Many consider it to have begun in CY-9784 when the Nietzscheans launched their Rebellion against the Commonwealth. It was not until 10092 when Tarn Vedra rejoined the known worlds that many consider it to have ended. The period was filled for many with Magog Infestation and Slave Raids while others endured near Slave light conditions, living on Tributary Worlds.