Judging by the timeline, Necromancers might still be part of the Mages, with their separation occurring around 751-750. The first eclipse happened in 330. The 4th race is most likely Elves, as the Elves haven't settled yet. This doesn't seem to affect the Dwarves. The Orcs are busy with their migration, and the 5th race is most likely beastmen created by mages (512).
Bow down and hear our cry,
Our earthly rulers falter,
Our people drift and die,
The walls of gold entomb us,
The swords of scorn divide,
Take not thy thunder from us,
Take away our pride.
G.K. Chesterton: English Hymnal