When
Ixion seduced the
Hera illusion, the illusion gave birth to
Centaurus (a depraved human boy).
Centaurus then mated with the mares of
Mt. Pelion in
Magnesia, giving birth to the race of
centaurs.
Note: Though
Chiron is often referred to as
King of the Centaurs, he is not a descendant of Centaurus, but rather the son of
Cronus and
Philyra.