I think it will be needfull, first of all to declare, that I believe in the vedic scriptures, but that I'm still investigating the Puranas. Maybe I will not live long enough to investigate them all. Before I started investigating the vedic scriptures, I had a project going on, to investigate the prehistory of mankind as far as possible. This led me from the greek/roman authors to the egyptian (Manetho), after that to the babylonean (Berossos), then to the calendar of the so called "sun gate" of Tiahuanaco and finaly to the vedic literature. My statement here I will support with the fragments of the writings of the babylonean priest Berossos and the vedic literature as far as I know it till now.
On the basic of my knowledge of the scriptures I am very sure, that Berossos used an indian source for his work about the history of Babylonia, which is now only available in fragments. I will proof this statement: "Berossos says, that he uses records, which are 480.000 years old and contain 2.150.000 years" (Paul Schnabel: Berossos und die Babylonisch-Hellenistische Literatur, Leipzig Berlin 1923, Reprint Milton Keynes UK 2010, page 175 f., my own translation). In Caius Plinius Secundus Natural History 7, 57 (193) are mentioned 490.000 years and the 2.150.000 years are mentioned at the beginning (in the german version p. 6) of the armenian version of the Chronicon of Eusebius of Cesarea. In Verbrugghe & Vickersham: Berossos and Manetho, p. 43 this number is reduced to 150.000 without any reason as also by Paul Schnabel the 490.000 years of Plinius are reduced to 480.000 years without giving any reason. But nevertheless this number is important. Berossos tells also (Verbrugghe & Vickersham fragment F3, p. 47), that before the great flood, which according to fragment F5 took place 33.091 years "before the medes … took Babylonia" (p. 52) which means round about 33.500 BCE, ten kings ruled for 432.000 years. These ten kings are also mentioned in Aitareya Brahmana 8.4. 21 – 23, where the Earth also prophesy the coming flood. This is one of the reasons why I'm equating this flood with that flood of the Puranas. This flood took place at the end of the Tretayuga and Manu Vaivasvata and his brother Yama were Survivers of it.
Let us now just count: this flood occured according to Berossos about 33.500 BCE, and before that date 10 kings ruled for together 432.000 years. That means the ruling of this 10 kings started about 465.000 years BCE. But Berossos tells us, that he uses records which are 490.000 (or according to Paul Schnabel 480.000) years old. That means, this records were recorded 25.000 or (according to Paul Schnabel) 15.000 years before that era of the 10 kings. If that era was, even though it lasted for ony 432.000 years, equal to the Tretayuga of the vedic scriptures, the records, Berossos used, would have been recorded at the end of the former Kritayuga (also called Satyayuga). This is the 1. reason, why I think, Berossos has used the Surya Siddhanta as his source, because in Surya Siddhanta 1, 2 f. and 1, 57 it is stated, that this was the time, it was written. The 2. reason for this interpretation is very easy: If you add the 432.000 years (of the length of the Tretayuga, as I think) of Berossos to the 1.728.000 years of the length of the Kritayuga according to the vedic scriptures, you got 2.160.000 years. This is also the number, Paul Schnabel uses (but he calculated wrongly into the future!), and that's probably the reason, why he reduced the 490.000 years, mentioned by Plinius, to 480.000 years and added the difference of 10.000 years to the 2.150.000 years, mentioned by Eusebius of Cesarea. However this may be, I'm absolutely sure,
1. that Berossos used the (original! it is modified several times) Surya Siddhanta as his source,
2. that the 2.150.000 years, mentioned by Plinius Secundus, in reality meant 2.160.000 years,
3. that the great flood, mentioned by Berossos, is the same flood, mentioned in the vedic literature,
4. that therefore the vedic yuga system is really old (it comes from Kritayuga!), but counts in a way, which is no more correct because of changes, mentioned in the vedic scriptures.
I hope, you can follow my argumentation, which I kept very short, to make it more understandable. I'm absolutely sure, that this is the truth (and there are other arguments for that too), that's the reason, I posted it here. I'm of course not interested, to ridicule myself. On the other hand I think, that this will be very important for indian people, provided they are interested in the truth and not in defending their sectarian believes.