The precessional movement of 54´´, peculiar to the Sûrya-Siddhânta, being referred to "Revatî" with its 4´´ direct motion, gives 50´´, like ours.
It is as well perhaps to recall what Iamblichus states:
The Assyrians have not only preserved the memorials of seven and twenty myriads [270,000] of years as Hipparchos says they have, but likewise of the whole apocatastases [planetary sidereal periods] and periods of the seven rulers of the world. (Proklos on Plato's Timaios, Bk. 1.)
H. P. Blavatsky, commenting on this, says it is
about 850,000 years since the submersion of the last large island (part of the Continent), the Ruta of the Fourth Race, or the Atlantean; while Daitya, a small island inhabited by a mixed race, was destroyed about 270,000 years ago, during the glacial period or thereabouts. But the Seven Rulers, or the seven great Dynasties of the divine kings belong to the traditions of every great people of antiquity. (The Secret Doctrine, I, 651.)
She also informs us that
The chronology and computations of the Brâhman Initiates[2] are based upon the Zodiacal records of India, and the works of ... Asuramaya. The Atlantean zodiacal records cannot err, as they were compiled under the guidance of those who first taught astronomy, among other things, to mankind. (The Secret Doctrine, II, 49.)
[2] But these are not the modern Brâhmans, as is clearly explained in H. P. Blavatsky's own writings.—F. J. D.