The Sokoro Union was a powerful Thannish nation that existed in the late Third Age.
During the Third Age, a band of pirates were defeated by a Thannish adventurer named Varis Sokoro, whose followers then established a settlement on the site of the pirate's' base/ This settlement was named "Varistan." In less than a century, Varistan grew ten-fold and became the thriving capitol of a civilization called the Sokoro Union. The Union was ruled by a series of self-styled “Princes,” who built the grand Sokoro Palace, a fortress overlooking the city which is, today, called "the Citadel." .
So it came to pass that in the last century of the Third Age, The Union was to be engulfed in the events of the wider world and lose its independence forever. Around that time, the growing nation of Valdor was expanding north; under the aggressive ruler-ship of Valden the Conqueror. Valden’s armies marched on Varistan in the year 1225/3, and Meraxas; the last Prince of the Sokoro Union, surrendered the city to him soon after. At that point, Varistan became part of the kingdom of Valdor and lost its independence forever.
Not all the peoples of the Sokoro Union chose to submit to Valden's rule, and several groups fled into the secluded nearby hills. Today, their descendants are called the Velskar; fierce tribes who constantly plague travelers and rural villages in eastern Eldara.