12 Biggest Unanswered Game Of Thrones Mysteries

3. Sothoryos

The 'Known World' of Ice and Fire is made up of four main lands: Westeros, Essos, Sothoryos, and Ulthos. The first two we know reasonably well, and even then there are lands to the far north and east (like Asshai) shrouded in mystery. Ulthos, meanwhile, may or may not be a continent, and largely exists to emphasise how little the people of Westeros know about that side of the world.

That leaves us with Sothoryos. It lies, as the name suggests, to the south of Essos, and we don't even know how big it actually is. The northern part of the continent has been mapped, but the south largely a secret. What's more, though, is that the land holds terrible dangers for pretty much anyone who tries to visit.

It's home to unique animals and all kinds of diseases of various shades of disgusting: yellowgum, greyscale, green fever, Red Death, bronze pate, brownleg and so on. Basically if you're stepping on Sothoryos, you've got about a 90% chance of catching one of these illnesses, but no one really knows how or why it's so dangerous to inhabit.

The city of Yeen, meanwhile, is an even bigger enigma, and its origins are considered one of the greatest, most vexing mysteries of the known world by the maesters of Westeros. It's built using oily black stone with blocks so big it'd require 12 elephants to move them, and despite the dilapidated state it's lain in for centuries the surrounding jungle has never encroached on the city itself.

Some of the surviving Rhoynar spent a year in Sothoryos and a few settled in Yeen - but when a boat was sent downriver to check on them, it turned out all men, women, and children had vanished without a trace, and the Princess Nymeria reportedly called it "a city so evil that even the jungle will not enter."