The map in question https://www.reddit.com/r/DnD/comments/6egj45/5e_art_made_a_map_for_my_players_adventure/

The Falmoorian empire was once a blooming kingdom ruled by two brothers, Quin and Crowe Corain. The Corain brothers ruled their seperate part of the kingdom as their father had decided before his death, he didnt want any of the brothers being left out of the heratige. Quin ruling the city of Falmoor and Crowe being designated to build his own city that became Castle Crowe As years past Quin ruled his part with great respect towards his people and he was a loved ruler. As for crowe, he ruled also with great compassion and his people liked him aswell but as the years past Crowe took an intrest in dark magics.

Both of the brothers had been keen practicers of magic during their juvenile years. Quin focused on the magic of light and healing and soon became a graduete at the temple of Kord making him a royal cleric. Crowe was a prodogy when it came to the arcane arts and he soon surpased the other pupils at the collage of arcane arts in Falmoor. Corwe used his magic to both fend of intruders and also to magically enhance the land resulting in no more bad seasons of harvest.

Fast forward a decade and Crowe has become bored he has mastered the arcane arts and now turn towrds new magical discoveries. Necromancy in perticular caught his intrest. Crowe started to avoid public events and was rearly seen anywhere by anyone other than the royal guards and his closest advisor. People in the city start to get arrested with crazy accusations never to be seen again. Soon rumors started to spred. Had their king gone mad? Shortly after the disappearence of habitants the agriculture started to decline heavily, people started to starve and with people starving and dying it wasnt long untill the diseases started so spread. First it was a fever, a few weeks after that people started to cough blood and had trouble breathing. This resulted in martial law within the city limits of Castle Crowe.

As Quin learned of his brothers kingdoms state he decided to act, he sent scouts and messangers to find out what was causing the horrible state of the northern parts of the empire. few of the scouts returned and thoose who did came telling terrifying stores of the dead walking, spectres roaming the streets, skeletal wizards controlling the hordes of death. Devestated by theese discoveries quin understood that he had to march upon his own brother. As the army of quin reached the Crimson Woods they were meet by a sight no living man should ever have to see. Thousands upon thousands of shambling corpses organized by powerful liches. The once blooming population turned to undead tools of war. the battle that transpired afterwards was a battle like no other. Wizards summoning thunder from the clouds crashing down upon the undead. Liches sucking the very life out of the soldiers making an atempt at charging them. As the battle progressed Quin realized that he was about to be defeated, the casulties he had suffered would render his kingdoom defensless if he didnt withdraw. In a last attempt to secure a victory he and his battle clerics made an assault towards Crowe, as they approached him Crowe didnt as much as hand gesture towards them. As the life of the clerics faded Quin stood there, spared by his brother in this moment of peril. "Join me brother" Crowe exclaimed "The powers that ive uncovered has no equal, we could make gods kneel before us". Quin looked at his brothers deluded face and with a simple calm sentince said "Im sorry brother, but youve lost your ways and i can not follow you ehere you tread" Quin clutched his amulet, prayed to his god and threw his divine mace at Crowe and as the divine light struck him he feel seemigly uncouncios at the groud untill Quin heard the most bloodcurling laughter he had ever heard. "Do you really think you could stop me that easily?" Crowe uttered "Let me show you what true might is made of". Before Quins eyes he saw his own brother levitate above the ground and unleash a massive torrent of necrotic energy filling the battlefield. The undead army withered as what little lifeforce they had was used in the spell, the living crumbled to the ground except for a few holy warriors who whitstood the massive amount of nercotic magic.

Defeat was certain Quin retreated and his clerics with him. Crowe returned to his castle with his liches, it would take time to assemble an undead army of that size again and he had expended alot of his own energy in the procces.

Years after the calamity that was the "war between brothers" the land of the battlefield have turned, no living being can tread upon the cursed grounds without turning mad and ultimatly turn into the very thing that the men fought there on that dreadful day.

Quin now remains a husk of his former self the exposure of dark necrotic magic left a mark upon his body, he is weaker than a man who has lived multiple lifetimes but his body refuses to die. Some belive this is a curse set upon him by his brothers, others claim that he can not pass on untill Crowe has fallen.