Galactic history, as a record of intelligent life, can be easily divided into two periods of time commonly referred to as the First and Second Epochs. The First Epoch refers to galactic history from the beginning of the universe until an event known as "The Sundering", the Second Epoch follows this event and may also be referred to as the "Living History", "Common Era", or "Post Extirpation".

The Sundering itself is a relatively broad time period where the cosmological (geological + space) record shows that all known civilizations had died out. The period itself exists within the First Epoch and there is no truly precise dating of when the Sundering begins and exactly when it ends due to the limitations of various dating technologies and the available evidence. Roughly speaking, the Sundering is a period of about 10,000 cycles, during which civilizations throughout the galaxy underwent decline and eventual extinction. After the Sundering there seems to have been no intelligent life in the universe until new organisms evolved sentience and began exploring space.

The period in which this second generation of civilizations appeared is rightly considered the Second Epoch. There is no direct evidence that a species from the Second Epoch has ever previously encountered living members of the First Epoch aside from very spurious interpretations of myths and legends. Indeed, until the advent of interstellar/planetary archaeology there had been no knowledge of a previous era of intelligent civilizations at all.

In general, the Second Epoch has been well documented by the galactic community, and essentially begins with the emergence of the Ukaros as the first interstellar civilization after the Sundering. Many histories simply begin with these events and do not refer to the Second Epoch or attempt to catalog specific events or timelines therein because of the sheer paucity of accurate information from the period.

The greatest archaeological question facing the galaxy is simply "What was the Sundering?" and all attempts to clearly define it or its cause have failed. If one is to accept the available evidence and postulate no further, than apparently over a dozen spacefaring interstellar civilizations and dozens of less advanced civilizations went extinct for a wide variety of unrelated causes all at about the same time in history. The Sundering explains the Terran "Fermi Paradox" of "Why isn't the galaxy rife with intelligent alien life?" circa the Terran twentieth century quite simply... there simply were too few spacefaring civilizations at the time to readily observe, as all others had previously died off.

This question of the Sundering is in itself a new paradox... how is it possible that dozens of civilizations went extinct at the same time... coincidentally?

Many believe the true answer is that they did not... and that some unknowable pan-galactic catastrophe was responsible for all of these civilization's ultimate demise.

This is a sobering thought, because surely, if it happened once, it could happen again.