Royal bloodlines

I have heard that many royal families in Europe are related to other royal families in some ways. I know that British royalty are descended from German Royalty and would like to know how far back we can trace their ancestry to other royal families or other people of power and influence.

Perhaps the extent of this is exaggerated to some extent and that is what I am trying to find out. Many of you are from Europe and (presumably) have a better understanding of this than I do. How far does this really go? Can anybody help me find out?

Charlemagne, maybe. But there were many non-marital children, so the blood gets "tainted" pretty quickly.

Haemophilia in the Royal line apparently comes from Queen Victoria.

That wedding? Royale with cheese ...

The recorded genealogy of the British Royal Family traces back to the Early Middle Ages

http://en.wikipedia.org/wiki/Genealogy_of_the_British_Royal_Family