When Men'heva founded the first pagan cult in the Eastern Kingdoms, he used them to build Karazhan. He then housed those first followers in Karazhan. Out of Karazhan, missionaries were trained and sent out to spread the Four religions amongst the godless humans. Cults and orders were created and seeded throughout Azeroth, such as the Hareveim.
It was to Karazhan that a forlorn Amron Radiun Malad travelled, and it was there that he completed his training as the Bruxist Highfather and Maroon Templar.
Karazhan remained the base of operations of Men'heva's loyalists throughout the Great War.