Great Swamp

The Great Swamp, was a location near the lands of Lordran, founded by the survivors of the Demon War in Izalith.
=== The Witch and her Chaos ===
When the Witch of Izalith started experimenting to try and recreate the First Flame, she instead made a flame of chaos, that erupted and consumed most of Izalith with its magical fire. The Witch herself was transformed into a great warped Bed of Chaos, her children transformed into Great Demons and most of the inhabitants into deformed monstrosities, coming to be known as Lesser Demons. Lord Gwyn, upon hearing of this catastrophic news, decided to venture into Izalith himself and see the carnage for himself. Disgusted by what he saw, he ordered the immediate execution of all demons in Izalith, but the Witch refused, stating that they were all her children. In response to this, Gwyn marched on Izalith with his army of Silver Knights, but eventually losing the short Demon War, instead he sealed the entrance dooming Izalith.
=== Discovery of the Great Swamp ===
Some people however managed to evacuate the city before being consumed by the Chaos and went on to living on the road for a while. Eventually they found a Great Swampland, which gave them an affinity for casting fire spells and magic, much like Izalith did and so founded a new civilization within this Great Swamp. It became known for the creation of new pyromancies outside of Izalith, teaching those that would be willing to journey to the land, becoming a new school for pyromancers.
Shortly after their settlement and subsequent practice of Pyromancy, they awoke a Great two-headed Serpent that had been asleep there for a long time and were said to have been primordial serpents similar to that of Frampt and Kaathe. The Serpent began to try and lay waste to the settlers, however the power of the pyromancies was too strong for the Serpent to keep up and they managed to overwhelm it in short time. However instead of slaying the serpent they managed to tame it, turning it into a form of guardian for the swamp. They also adapt the twin-headed snake as their symbol. 
=== And Then Came Lothric ===
Long after the Kingdom of Lordran came the Kingdom of Lothric, which expanded its lands drastically, taking land from several neighbouring countries including that of the Great Swamp. Eventually the Great Swamp fell to the forces of the Lothric and the swamp became completely part of the lands. Eventually the villages formed in the Great Swamp became known as the Undead Settlement due to the amount of Undead that lived there and were given their own governance as well as being allowed to continue the practice of Pyromancy. Farron Keep also settled on parts of the Great Swamp. What happened to the Twin-Headed Serpent is unknown, though rumour has it was that it escaped the swamp and began inhabiting the five finger delta, hiding amongst the desert lands.