Our story began in 1340, The Year of the Lion.
The Surbrin Valley was the rocky vale formed by the River Surbrin in the Savage Frontier of northwest Faerûn. It extended from the Spine of the World in the north to the Evermoors in the south, and between the Moonwood in the east and the Frost Hills in the west.  Two miles below the vale, something dark and tragic resides.  Few have let journeyed into the great depths to discover the City of Spiders… and none have returned.
Menzoberranzan is an underground city populated by the drow, and ruled over by Lolth. The city has 20,000 drow inhabitants and hundreds of thousands of humanoid slaves such as goblins, kobolds, bugbears, duergar, svirfnebli, orcs, ogres, minotaurs, and giants, as well as herds of rothé kept as livestock.
The city trades poisons, mushrooms, riding lizards, spell scrolls, wine, and water.  The worship of Lolth is absolute; the clerical academy Arach-Tinilith controls training of all priestesses, and the uncovering and destruction of any rumored heresy.
One of the branches of the city's triune academies of Tier Breche, Arach-Tinilith is neighbored by the warrior school Melee-Magthere, and Sorcere where arcane spellcasters are sent to study. These academies are the quarters of some of the most powerful clerics, fighters and wizards, respectively, and the title of master of an academy is coveted, since being the master of Sorcere or Melee-Magthere is as high as the power ladder goes for some houseless drow or even noble males.
On one edge of the city the family houses are located in their glory, while the edge near the lower level Drow houses there is a lake used to water the rothé. An island in the center is used to as an outlook post to help defend the city.

In 1356, houses are unified after turning back the mate of the shadow dragon Shimmergloom, and the World Below has become fairly static.  This is where our story continues, as a budding house has climbed in just sixteen short years to dominate the food supply for the entire city of Menzoberrazan. They have also through the course of their machinations learned terrible secrets about their own formation and the ancient history of their people.
An ongoing rivalry between Agrach Dyr and Horlbar continues to threaten that peace, but with their sizes fairly even none has advantage to press an attack, and neither is willing to wait out that doleful year before another house wipes them out for their seat on the council.