I found the following about the origins of the Zwarte Piet (Black 
Pete) tradition in the Netherlands and Belgium in The Netherlander of 
December 6 :

"Fact : Black Pete was invented by Amsterdam schoolteacher Jan 
Schenkman in 1835 in the book 'Sinterklaas and His Slave'. Black Pete 
was most likely introduced because it of the fashion among the rich 
people of the day to have black pages. The dumb, jolly but cheekily 
servile Black Pete was invented by an author writing 28 years before 
the slave trade was abolished in the Netherlands in 1863. In 
addition, Schenkman made Black Pete a Moor. So not only do we have a 
symbol of black oppression, but also of the dominance of Christianity 
over Islam."

The article pretty much calls for the abolishment of Black Pete. It 
opens with the line "There's something rotten in the state of the 
Netherlands." which I thought was a bit far fetched. But as a 
discussion about whether the critics of Black Pete are right is 
outside the scope of the list, I will leave you with the quote.