Valyria is a nation of southern and western Essos, governed by the Freehold. Rather than be ruled by a single Prince or King, the Valyrian Freehold is council of land-owning lords, and all landed citizens are permitted a voice. No one family holds sway over all at the moment, though at times in the past this has happened.
Valyria owes much of her power to the strange science of her pyromancers and especially to the Valyrian breeding and control over dragons, which no other people have been able to emulate or explain. The power of their dragonriders enabled them to defeat the ancient empire of Ghis and were the deciding factor in the defeat of the Rhoynar host under Prince Garin the Great, shattering the might of the Rhoynar for good and making the Freehold the greatest power in Essos from the Narrow Sea to Slaver’s Bay.
Although the Freehold consists only of the lands upon the actual Valyrian peninsula, those territories they have conquered are considered part of a growing Valyrian empire. Now that Ghis and the Rhoynar have fallen, Valyria has turned her eyes towards Andalos, pushing more Andals to head towards Westeros in refuge.
Some power within the Fourteen Flames or in the fire of dragon’s breath has allowed Valyria to produce a type of steel unique to their civilization. Valyrian steel is lighter and more durable than any other known variety of steel, but most important in the last several decades is the fact that it is one of the only substances known that can kill The Others and it was instrumental in ending the Longest Night. The Night’s Watch now eagerly pursues the acquisition of further Valyrian steel weapons and strives to have a dozen at every one of its growing number of fortresses along The Wall