We covered the ancient aqir and their qiraji descendants last week. What we didn't really cover was the group of arthropods who headed north, enslaved the Ulduar region's tol'vir and founded ancient Azjol'Nerub. From the time of their expulsion from the central part of the ancient supercontinent of Kalimdor by the Gurubashi and Amani trolls, to their defeat and subordination of those tol'vir, and up to their recent near-total destruction by the Scourge during the War of the Spider, the aqir offshoot calling themselves nerubians have existed apart from their southerly kind. While the qiraji serve C'thun, the nerubians seem wary of the Old Gods and their Faceless Ones, even when gripped by the Lich King's undeath.
Furthermore, while many nerubians ended up in the service of the Lich King, forcibly resurrected by him, it's telling that the nerubians were immune to the plague of undeath and waged a war against him for over a decade, only losing when they found themselves trapped between the servants of the Old Gods and the dreadlords that at the time served as the Lich King's advisors and jailors. Their immunity to the plague did not confer immunity to undeath when directly raised, and so Anub'arak, last king of the nerubians, ended up a slave like much of the rest of his race.
As of the pre-Cataclysm world, nerubian undead can be found in the plaguelands serving alongside the Cult of the Damned as well as in Northrend itself, while the battered and hateful remnants of the empire of the nerubians are so desperate that they'll accept help from the races of the Alliance and Horde.