1) At some point in the distant past humans on the distant planet Kobol create a type of robot called a cylon, possibly for menial and dangerous work. At some point in the evolution of this robot a model is created which is almost indistinguishable from human beings. The largest difference seems to be that the cylons didn’t reproduce sexually. Instead, their memories and personality are directly transferred from one body to another. This type of cylon would come to be nicknamed “skinjobs” by the humans in the series;

2) Approximately 4,000 years before the series a group of skinjobs leaves Kobol, eventually traveling to Earth. This group may also have included humans. They travel thousands, or tens of thousands, of light years at superluminal speeds, stopping at least once to build a temple on a habitable planet. This group will come to be known as the 13th Tribe by the humans in the show;

3) Approximately 3,600 years before the series, there is travel or a transfer of information from Earth to Kobol. Among the data is some information about the journey of the 13th Tribe to Earth and the names of several constellations and what they look like when viewed from the night sky on Earth. Some of this information makes its way, in some form, into the religious works of the humans on Kobol;

5) At some point after the 13th Tribe settles on Earth the skinjobs who travelled begin to procreate sexually and lose their ability to directly transfer memories from one body to another;

6) At some point after this, five skinjob researchers successfully build a technological version of the biological memory transfer abilities they used to have. In the series these five will come to be known as the Final Five;

7) At some point after the 13th tribe settles on Earth they create a type of robot known as a centurion, presumably for dangerous and menial work;

7) Approximately 2,000 years before the series, on Earth, something happens which results in almost all of the planet’s surface getting nuked. It seems at this point the centurions revolted against their skinjob (and possibly human?) masters. The Final Five receive some kind of warning or premonition but are unable to stop it. The Final Five, and presumably all other skinjobs on Earth, are killed. The Five are resurrected on a ship orbiting Earth and take off towards the 12 Colonies at relativistic but subluminal speeds in order to stop the same thing from happening to those who stayed behind thousands of years before. The speeds are fast enough so that time dilation is significant, but slow enough so that the journey takes approximately 2,000 years from the viewpoint of the humans and cylons in the 12 Colonies;

4) Approximately 2,000 years before the series the humans who remained on Kobol leave the planet. They eventually settle on twelve planets which lie in the same general region of space. These planets come to be known as the 12 Colonies;

8) Several decades before the series begins the humans in the 12 Colonies create their own centurions. Shortly after this the centurions on the 12 Colonies revolt and wage an extended war against the humans. At some point in this struggle the centurions begin to experiment on captured humans in order to create a human-looking cylon. They are unable to do this, but do create a human/cylon hybrid known as a Hybrid. The war ends suddenly with an armistice and the centurions effectively disappear;

9) At roughly this time the Final Five reach the region of space in which the 12 Colonies and the centurions live and attempt to strike a deal with the centurions in which the Final Five will build them skinjobs, and presumably give them resurrection technology, in return for an agreement from the centurions not to attack the humans. This deal may have precipitated the end of the war;

10) The Final Five build eight new skinjob models. One of these models, named Daniel, is effectively killed by the first of the new skinjobs, known as John to the Final Five and Cavil for most of the series;

11) Cavil/John, thirsting for revenge for what he perceives as cylon slavery, kills the Final Five, suppresses their memories, and scatters their resurrected bodies throughout the colonies;

12) At roughly the same time the centurions and the new skinjobs attack the colonies, killing almost all of the humans. About 50,000 humans escape, mostly because of luck and circumstance;

13) The series starts.