Think about it. Paper was invented in China - one of the most important and world-changing technologies of all time by the way. It was invented long after Marco Polo brought back gunpowder and pasta - but long before any other Europeans ever ventured anywwhere near China again.
And it became common throughout Europe long before Europe re-established trade with China - in the middle of the nearly thousand year gap between Polo and the next European to reach China.

How did it get there ? Europeans didn't invent it independently. They didn't get it from the people who DID invent it (the Chinese)... so how did they get it ?
They got it from the people who WERE trading with the Chinese in those centuries: the Africans. Paper was imported into Europe by the Moors during the conquest of Spain. The Moors were black people from Africa. It was just one of many technologies in use in Africa that the Moors brought to Europe. Different parts had different technologies. But none were "backward".