The concept of Sub Races is related to Root Races, in that Sub Races are a subdivision of Root Races. In href="http://www.theosophical.org/theosophy/faqs/index.html">Theosophy there are seven Sub Races for each Root Race. Steiner maintained the structure, but renamed the Root Races "Epochs" and the Sub-Races "Cultural Epochs" and specifically de-emphasized the racial aspects.
In 1908 Steiner said:
"When people speak of races today they do so in a way that is no longer quite correct; in theosophical literature, too, great mistakes are made on this subject ... Even in regard to present humanity, for example, it no longer makes sense to speak simply of the development of races. In the true sense of the word this development of the races applies only to the Atlantean epoch ... thus everything that exists today in connection with the [different] races are relics of the differentiation that took place in Atlantean times. We can still speak of races, but only in the sense that the real concept of race is losing its validity."
Steiner, Rudolf. Universe, Earth and Man (GA 105), London 1987, lecture of 16 August 1908.
"For this reason we speak of ages of culture in contra-distinction to races. All that is connected with the idea of race is still a relic of the epoch preceding our own, namely the Atlantean. We are now living in the period of cultural ages ... Today the idea of culture has superseded the idea of race. Hence we speak of the ancient Indian culture, of which the culture announced to us in the Vedas is only an echo. The ancient and sacred Indian culture was the first dawn of post-Atlantean civilization; it followed immediately upon the Atlantean epoch."
Steiner, Rudolf. The Apocalypse of St John (GA 104), London 1977, lecture of 20 June 1908.
Explaining the issue at length in 1909, when he was still the General Secretary of the German section of the Theosophical Society in Germany, Steiner said:
"If we go back beyond the Atlantean catastrophe, we see how human races were prepared. In the ancient Atlantean age, human beings were grouped according to external bodily characteristics even more so than in our time. The races we distinguish today are merely vestiges of these significant differences between human beings in ancient Atlantis. The concept of races I only fully applicable to Atlantis. Because we are dealing with the real evolution of humanity, we [theosophists] have therefore never used this concept of race in its original meaning. Thus, we do not speak of an Indian race, a Persian race, and so on, because it is no longer true or proper to do so. Instead, we speak of an Indian, a Persian, and other periods of civilization. And it would make no sense at all to say that in our time a sixth "race" is being prepared. Though remnants of ancient Atlantean differences, of ancient Atlantean group-soulness, still exist and the division into races is still in effect, what is being prepared for the sixth epoch is precisely the stripping away of race. That is essentially what is happening.
Therefore, in its fundamental nature, the anthroposophical movement, which is to prepare the sixth period, must cast aside the division into races. It must seek to unite people of all races and nations, and to bridge the divisions and differences between various groups of people. The old point of view of race has physical character, but what will prevail in the future will have a more spiritual character.
That is why it is absolutely essential to understand that our anthroposophical movement is a spiritual one. It looks to the spirit and overcomes the effects of physical differences through the force of being a spiritual movement. Of course, any movement has its childhood illnesses, so to speak. Consequently, in the beginning of the theosophical movement the earth was divided into seven periods of time, one for each of the seven root races, and each of these root races was divided into seven sub-races. These seven periods were said to repeat in a cycle so that one could always speak of seven races and seven sub-races. However, we must get beyond the illness of childhood and clearly understand that the concept of race has ceased to have any meaning in our time."
Rudolf Steiner. The Universal Human: The Evolution of Individuality. New York: Anthroposophic Press, 1990. Pages 12-13. Lecture of December 4th, 1909.