Santa Claus

I wonder where all the different traditions concerning Santa Claus and christmas gifts come from.
In the U.S. Santa Claus comes through the chimney and you will have your presents on the 25th’s morning.
In Germany Santa Claus comes on the sixth of December. He comes at night and when you wake up on the sixth he was already there and has left you a few chocolates in your boots. I can remember discussions at kindergarden when at some families’ Santa Claus already came on the evening of the fifth. But this is wrong, every calender shows the sixth as the day. But on the sixth you get only chocolates, the really big presents you will receive on the 24th, not from Santa, he is only in charge of the sixth of December – in Germany we have the Christkind for Christmas Day (December 24th) .
I learned from my husband that it is completely different in the Netherlands (and according to my cousins boyfriend from Antwerp it is in Belgium aswell). Santa Claus comes on the sixth on a ship from Spain, together with “Zwarte Piet” a black boy who helps him to give out the presents and who will give a little pack of salt to those who haven’t been good. On the 25th you will only receive chocolates.