Nantu was the city that served as the headquarters of the Order of Lorekeepers, which was where their Council of Elders would be found. The Council of Elders were members with privileged access to the tomes of "Greater Wisdom." Their function as keepers of knowledge from following the Arkati was effectively replaced with the later lore of Chronicle keepers who helped form Ta'Illistim. "The Council of Elders" in the context of House Illistim were high-ranking Loremasters with almost full access to Library Aies. Adonethwen Illistim, granddaughter of Linsandrych, was a Lorekeeper.
The city was famous for its university, often called the Great University of Nantu. Nantu does not appear on any known map of Elanthia. It might have begun as a re-named I.C.E. Age term, functionally replacing Karilon in backstory but most likely starting as an inconsistent shifting of Nomikos (which is more familiar as "Biblia"), which became out-moded with later development. The relationship between the Lorekeeper society and Illistim state is not clear.
Behind the Scenes
"Scholar from Nantu" below was probably "Scribe of Nomikos" originally, possibly in reference to the obscure dead language used for most of their scholarship.
- Moot Hall
Pulling out an odd-looking pair of round glass disks, the clerk peers through them at some faded notes written in the margin of a massive sheaf of parchments. He squints at them in puzzlement and shakes his head while muttering, "Not even a Scholar from Nantu could read THIS gibberish!"