As I can read, the author of the series created several books in the series starting with the book A Game of Thrones. I'm watching the series on TV (I haven't read the books).
When I watched something in the show that I do not fully understand or want to brush up on, I go search the web and usually find the information in Wikipedia. Often I also find a full timeline from before the first book, and I wonder where does this information come from? Whoever wrote this must have this information from somewhere - I just don't seem to understand where, since the first book starts around the same time the first episode of the first series in the TV show?