I am a bit confused about those few points and i am not sure if they were explained in the last couple of episodes or not, so if anyone can help me with them it would be very much appreciated.
1- I don't get who attacked the original cylons, where they humans or an another type of A.I. created by them?
2- If the 13th tribe (the cylon tribe) split from the original 12 thousands of years ago, does this mean that the humans created advanced cylons thousands of years ago, but then somehow regressed technologically?
3- Did they state that the 13th tribe was pure cylons with no humans at all? (if it was mixed or originally completely human, then it could be the 13th tribe humans who initiated the cylon genocide on earth which would be much more logical and could explain a lot of things, also it could mean that there still is an existing human civilization somewhere)