King of Winter and Ice (asoiaf)

When Valyrians started their conquest, Andals neither wanting to bend to them nor become their salves fled towards Westeros. They arrived on the land that is called Fingers in the Kingdom of Vale. It was ruled by many petty kings who welcomed them with open arms after seeing how they have better arms and armor. They sought the knowledge of andals and their numbers to fight in their wars. The andals agreed but they have much more sinister plans. After helping them in conquering the surrounding lands they betrayed them and themselves became the rulers of the land. They started mass conversion to their faith which is called the Faith of the Seven based on their seven gods and follows the book name Seven-Pointed Star, on the edge of sword, killing those who refused to burn and raping their women.

As more Andals arrived they started conquering more and more lands. The Royces and Griffins tried to stop them but were eventually defeated. House Royce decided to bend the knee to the new King of House Arryn and survive but still kept to their religion along with many of those who were once their vassals. The Griffin Kings were defeated and their whole line became extinct. His followers and many of those who still refused to convert decided to hide in the tall Mountains of the Moon and to keep fighting by guerilla tactics. They were never able to retake their lands but no andal lord was able to relax because of them.

From Vale, they spread to their only neighboring kingdom, the Riverlands which were ruled by Tristifer IV of House Mudd. He battled many Andal warlords over the year and fought against them in 100 battles, 99 of which he won and died fighting the last battle. His son Tristifer V Mudd became the king after him, but he was not as capable as his and the Kingdom was soon overrun by Andals but before dying he was able to spirit his son to the North to the Starks who made them Lords of Stony Shore after they showed their prowess against the andals.

After this, they were welcomed open armed by the Reach and Westerlands. Reach because they House Hightower and Gardener both wanted to become Kings of Reach and were a bunch of cowards and Westerlands because House Lann who wanted to become rulers of whole Westerlands needed their support. So Tytos Lann, decided to marry his only child and daughter to the strongest andal warlord of that time Joffrey Starr. Together their House was called Lannstarr which later became Lannister and using the Andal might they became the rulers of Westerlands.

They tried to convert Stormlands with their might but failed again and again. So, in a surprising show of cunning, the andals instead of warfare used marriage. And slowly but surely converted the faith of the land as well. Dorne gave mixed results. Dorne is a desert area rendering direct warfare against dornish a costly affair as they were masters of guerrilla warfare. So instead of sending armies they send their septons and septas to peacefully convert them.

When these kingdoms were converted, they started burning down weirwood trees and killing the Children of the Forest and Giants calling them demons. They fled all over the continent and hid in secret places deep in mountains, God's Eye, north of the Wall etc. Now only North remained as the last bastion of the Old Gods.

Argos Sevenstar, an Andal warlord decided that he is going to rule the North, but he didn't know that his biggest nightmare is going to meet him there. Argos and his fleet landed near the mouth of river Weeping Water and started their old business of converting them at sword point, raping, looting and burning weirwood. When Theon Stark, the Hungry Wolf, heard of this he vowed that he would burn 10 septs for every weirwood and kill hundred andals for every child of the forest. Seeing the threat of Andals the Red Kings finally bowed to the Starks and asked for their help. Theon proved his mettle and defeated the andal warlord and captured him and his seven sons alive.

Theon led them on the seven-day long journey to the Dreadfort to sacrifice them to the Heart Tree there. He killed one of Argos son every day in the most brutal manner he could think infront of Argos. On the eighth day, they finally reached Dreadfort where Theon blood eagled Argos infront of the Heart Tree. Then using the ships of Argos, on which Theon used the dead body of Argos as the figurehead, Theon sailed towards Andalos where he sacked every village and town, learned their secret of iron and steel working and built a huge mountain of skulls of his victims.

When he returned his ships were full of loot from Andalos and skulls. The skulls were hung on pikes on the coast of the North. Later he helped the order of Night's Watch, those who guard the realm from the Night King which they themself will forget sometime over the future, against wildlings, the scouts who agreed to stay north of the Wall but turned into savages over time. Then he fought against the Ironborn and got his west coast free of them and gave Stony Shore to House Mudd for their help against andals and ironborn. He also captured the island of 3 sisters to better protect his coast from a Southern threat.

By the time this was done North became one of the biggest naval powers of seven kingdoms thanks to ironborn, Argos Sevenstar and the navy of andalos which was taken by surprise at night and captured. Theon used the gold he took from andalos and iron islands to build roads and find a way to move in winter easily. This venture took a lot of time, but the stone carved roads and the invention of sledges and skis helped the northern economy to work in winter as well.

It was almost comical how the sledges and skis were invented. One day, young son of Theon, Rickon was playing with his direwolf whom he was using as a horse but instead of allowing him to sit on him the direwolf was running around and dragging Rickon with him, who have held the wolf by its tail, in the snow. There he got the idea of using elks and deers found only in the North to push a type of carriage without wheels that wouldn't sink in snow. and later skis were also made. It took proper channels of sledges and carts for areas not completely covered in snow, but the trade boomed in North after that.

It was not the last time that andals attacked North, but it was the last time they attacked from the sea. Southern kingdoms other than Dorne tried many times to enter the North through the Neck but were always defeated either in the Neck or at the Walls of Moat Cailin. Actually, these wars proved much more profitable for the North than any other war. The hostages that the North captures have to pay their weight in gold and food for winters. The gold was used in better fortifying the castle, increasing economy and overall improving the lives of North man.