Blavatsky
Original sense
Humanity evolves through seven great ‘root-races,’ each with seven sub-races, across enormous periods and changing continents. We are, in her clock, the fifth (Aryan in the old, broad linguistic sense, not the later political one), with remnants of the fourth (Atlantean) and third (Lemurian). The scheme is spiritual-physical, not a license she formally granted for colonial hierarchy — though her language is of its century and has been used that way.
The Third Race was the first that was truly human; the Fourth, the Atlantean, developed intellect; the Fifth is the race of the present cycle.
She mixed Sanskrit yuga theory, contemporary race science, and occult revelation. The result is neither modern genetics nor innocent allegory. Honest reading has to hold both: cyclic metaphysics, and a racial vocabulary that later harmfully escaped the book.