Different types of Nerubian are referred to as castes with a life-long occupation and responsibility in society. Seers, for example, are relatively high-level Nerubians who act as priests and mages. Spider Lords are the rulers of the society in the same mold as the aristocracy of humanoid races.
The spider is the most common motif of the Nerubians, and they have appear to have evolved partially into an arachnid race (eight limbs) from an insectoid race (six limbs). Despite the Nerubian cultural association with spiders (who reproduce through any male and any female), they reproduce as most insects do, through Queens.
Undead Nerubians are usually under control of the Scourge and are known as Crypt Fiends (in the case of most Nerubians) and Crypt Lords (undead Spiderlords). It is not known if Queens can be made undead, or what they are called if they can.
At the ancient continent Kalimdor's center was a mysterious lake of incandescent energies, the Well of Eternity. It was the true heart of the world's magic and natural power. From this magical ether the Silithid were born. As the fallen Old God C'Thun recognized their appearance, he attempted to sunder the world that it once held in its unmerciful grasp. The Old God created avatars from the Silithid in its own image. These avatars were to be known as the Aqir.and all information you can get your hands on pl0x
The Aqir ruled the lands of the far west. These clever insectoids were greatly expansionistic and incredibly evil.
The Aqir were obsessed with eradicating all non-insect life from the fields of Kalimdor. So the two big Troll empires of Gurubashi and Amani found their common enemy in the third empire - the civilization of Azj'Aqir.
The trolls fought them for many thousands of years, but never succeeded in winning a true victory over the Aqir. Eventually, due to the troll's persistence, Azj'Aqir split in half as its citizens fled to separate colonies in the far northern and souther regions of the continent.
Two Aqir city-states emerged - Azjol-Nerub in the northern wastes, and Ahn'Qiraj in the southern desert.
So the new kingdom of Azjol-Nerub that stretched like a great web beneath the desolate glaciers of the land later known as Northrend.
Thousands of years later when the Lich King extended his influence over Northrend, the shadowy empire stood against his power. The ancient subterranean kingdom of Azjol-Nerub, sent their elite warrior-guard to attack Icecrown and end the Lich King's mad bid for dominance. Much to his frustration, Ner'zhul found that the evil Nerubians were immune not only to the undead plague, but to his telepathic domination as well.
The Nerubian spiderlords commanded vast forces and had an underground network that stretched nearly half the breadth of Northrend. Their hit-and-run tactics on the Lich King's strongholds stymied his efforts to root them out time after time. Ultimately Ner'zhul's war against the Nerubians was won by attrition. With the aid of the sinister Dreadlords and innumerable undead warriors, the Lich King invaded Azjol-Nerub and brought its subterranean temples crashing down upon the spider lords' heads.
Though the Nerubians were immune to his plague, Ner'zhul's growing necromantic powers allowed him to raise the spider-warriors' corpses and bend them to his will. As a testament to their tenacity and fearlessness, Ner'zhul adopted the Nerubians' distinctive architectural style for his own fortresses and structures.
Though there are few pockets of Nerubian warriors left, they still seek to gain vengeance upon Ner’zhul and reclaim their subterranean kingdom. Groups of such can be found all over Northrend and even in the deepest reaches of their own city. A particularly large settlement is the Sundered Monolith.