Classes (Dawn Of Civilization Supplement)
From D&D Wiki
Because this setting seeks to replicate a lower level of advancement, there are only three starting classes;
Any PC must pick one of these for first and second level. At third level, they can diversify into the following advanced classes;
but only if their civilization level is 3 or higher.
Once their civilization level is at 6 or higher, they may then expand further into these prestige classes;