When talking about the map of Braavos for TLOIAF, illustrator Jonathan Roberts stated the following on his website:
"yes, look at this one carefully – there are locations on here that haven’t appeared in the books … yet"
In an interview for Quartz, however, Roberts was more specific in saying that he was sent unpublished TWOW material with instructions:
"I was sent a set of chapters from The Winds of Winter [the forthcoming sixth book in the series] in 2012, with geographic detail