Sages were the post-I.C.E. Age name for the Loremasters, the organization in the Shadow World history responsible for bringing back civilization. The Loremasters were founded to guide the lesser races by Andraax, a surviving Lord of Essaence from the First Era. Servants of the Unlife exploited resentment against them to corrupt rulers leading up to the Wars of Dominion. "Sage" when used in the archaic context referred to their mortal members or world traveling Scribes of Nomikos, though both organizations engaged in this activity. The Loremasters do not exist in modern Elanthian history.
The word "Sage" has since been retconned to refer to the Order of Lorekeepers. The Great University of Nantu was maybe replacing the College of Karilon. However, Nantu itself became somewhat archaic, its function replaced by Library Aies. Nantu has since been retconned out of the Lorekeeper history, which are now instead based in Ta'Illistim.
There are also the Masters of Lore in Ta'Illistim, which is the more modern meaning of "Loremaster." Notable Loremasters (archaic) included Uthex Kathiasas, Andraax, T'vaar Dekdarion, Elor Once Dark, and numerous others. Modern Loremasters (Illistim) included Meachreasim, Hiraani, Maraellynde, Illuvassas, and others, including Linsandrych herself. Uthex Kathiasas has been retconned as a Sage of the Order of Lorekeepers. Other known NPC Sages of the Lorekeepers have included Estrello and Sureshi.
Behind the Scenes
There were also "Loremasters" of the University of Magical Arts on Uman Isle, which was likewise founded by Elves but was unrelated to the College of Karilon. This was implicitly part of the world setting in the I.C.E. Age but never concretely existed. Uman Isle was developed early on but was never implemented as such. It was later turned into Teras Isle and given a dwarven history instead. This was only very distantly based as their major commonality was mostly just possessing a lot of glaes and the relative position of the Fhorian village on the island.