can someone give me a good explanation of the Dalek's history. I know Genesis of the Daleks changed their timeline a bit but it's confusing reading the synopsis of their appearances. It seems Hartnell and Tennant and everyone in between have fought drastically different Daleks. Also I think the main confusing problem is that some stories are given dates. When did Davros make them, when did Hartnell encounter them, when did they start becoming a big galactic threat, when did Davros wake up etc?
I know time travel is involved, but it's confusing, and not being able to see a lot of the early episodes makes it harder to figure out. can anyone clarify this?

Bow ties are coool.