The peoples of Kyor developed from three main heritages. The rigid caste system of the Elves, the goal-oriented guilds of the Dwarves, and the chaotic city-states of the humans. Each heritage includes a number of PHB races in them. Other races are also found in the world of Kyor, but their origin is more specific to a particular geography.
These heritages were created long before the main three heritages on the continent of Radavan, but waned as the three biggest ones grew.