Is the Secret Book of Dzyan, anthropogenesis and cosmogenesis, the Kalachakra teachings from Siddhārtha Gautama? It is said, in a legend, the King Suchandra (Tib. Dawa Sangpo), of the northeastern Indian Kingdom of Shambhala (a region), requested from the Buddha the Kalachakra teachings, or the teachings regarding the cycles of time. From this, was composed, what is named the ‘Root Text’ or Mūla-Tantra, said to be lost.
What David Reigle says is that the Secret Book of Dzyan is not plagiarised from the Kangyur of Alexander Csomo de Körös, but is the “lost” Mūla-Tantra.
The Mūla-Tantra is said to be, the original basis of the publicly known Kalachakra tantra.
It must be also noted, that what H.P.B. presented as the Stanzas is only a portion of the whole.
Helena P. Blavatsky stated a difference of the types of teaching on the tantras.
“(…) the “Dus-kyi Khorlo,” or Tibetan Mysticism. A system as old as man, known in India and practised before Europe had become a continent, “was first known,” we are told [by the Orientalists], only nine or ten centuries ago. The text of its books in its present form may have “originated” even later, for there are numerous such texts that have been tampered with by sects to suit the fancies of each. But who has read the original book on Dus-Kyi Khorlo, re-written by Tsong-Kha-pa, with his Commentaries? (…) this grand Reformer burnt every book on Sorcery on which he could lay his hands in 1387 (…) he has left a whole library of his own works – not a tenth part of which has ever been made known.” (Helena P. Blavatsky, A Few More Misconceptions Corrected, Blavatsky Collected Writings, Vol. 14; brackets added)