The oldest race known are the ehlnofey and the hist, later ehlnofey became aldmer and men, while some hist evolved into argonians.
Mer later become divided even more the dwemer,altmer,chimer, Orsimer and bosmer.
Dwemer are races that live in the underground of dwemereth, which now known as Morrowind
Chimer are mer that abandon the way of summerset Isle and go into exodus to Dwemereth following the prophet Veloth. Later after the battle of red mountain they were cursed by Azura and became Dunmer.
Bosmer are aldmer that settles in Valenwood and due to adaptation become the bosmer.
Orsimer are aldmer that are cursed when Boethiah defeat Trinimac turning him into Malacath
Those that remain in Summerset Isle became known as altmer
Men became three the nedes,nords,and yokudans.
The Nedes are those that remain in Tamriel
Nords are those that settle in Atmora but later migrate to Tamriel after the freezing of atmora that changes it into wasteland plagued by civil war.
Yokudans are those that settle in yokuda but later migrate to Tamriel after yokuda sank.
Later due to the mixing between nordic blood and nedes blood, Imperial came into existance.
While on high rock due to breeding between mer and men (the nedes) Breton came into existance.
Now if this is correct where does Khajiit came from?