Wallpaper wasn't a new in the 19th century, in fact, Eqyptian's were said to have used wallpaper. All sorts of wallcoverings have been used over the years, fabrics & thick hand woven wool rugs to name a couple.
In 1839 however, a machine was invented that changed wallpaper for ever. Prior to this invention the prints on the paper were block printing and hand painted on the paper. But once this wallpaper printer was invented. Image below:
Wallpaper became a product more and more people could afford. Potters of Darwen in Lancashire, England, adapted a printing machine for wallpaper and patented it 1839.