There seems to be a commonly held mistaken impression that all low generation vampires should be very, very old - while all high generation vampires should be very young. Everyone realizes that there could be a low generation Kindred that was embraced yesterday - and hence is extremely young - but for some reason, the reverse probability seems to be constantly overlooked. Unfortunately, White Wolf has - perhaps deliberately - perpetuated this myth with their 'Time of Thin Blood' writings. Because yes, it is indeed a myth, and I will show you why.

In several places, it is mentioned that Caine was disturbed by the fact that his childer in Enoch 'embraced indiscriminately' - in other words, they went mad with the embrace and created too many vampires. It seems the knee-jerk assumption here is that only the second generation were involved here. But, if the second generation allowed themselves unlimited embrace, why not the third, or the fourth, or the fifth? It is far more likely that there was No restriction on the embrace, and each generation spawned the next relatively quickly.
In another writing, it is mentioned that when Cappadocious called a conclave of his Clan some time in prehistory, he was dismayed to find over 10,000 vampires showed up - a fact that caused him to trap them all in a cave and bury them forever.
These two writings suggest something that common sense can easily see, if you simply look at it the right way.

There is no limitation on what age a given generation might be.

Consider this.
There may have been 14th generation vampires in Enoch before the time of the Great Flood. Even if each generation waited 50 years before embracing their first childer, it would only have taken something like 600 years or so to see the first 14th generation vampires wandering around.

So why isn't the world overrun by vampires of the high generations?
The answer is simple - repeated mass extinction.

It is logical to assume that only the most powerful and resilient vampires could survive a catastrophe like the Great Flood. Those of the higher generations would have been destroyed by such a powerful cataclysm - which was apparently precisely the intended purpose of the Flood. So, following this disaster, the Antediluvians would have had to begin again in creating new childer.
But again - it may have been only a relatively short time before there were 14th generation kindred underfoot everywhere - perhaps a bit longer because the Antediluvians were cautioned by the lesson of the Flood, but still not too long.

The writings say there was a second city, but that this too was destroyed - not by cataclysm, but by war. In any war between great powers - and especially between elder vampires, it is the lesser individuals that suffer - so again we can assume that the higher generations suffered another mass extinction during the fall of the second city.

And so it goes, from the wars of the Mediterranean to the fall of Carthage to the Anarch Revolt - there have been numerous periods in Kindred history when the high generations would have been the first to die off and only the very low generations would have likely survived.

But - this does not mean that those earlier high gens were wiped out to the last individual. It is highly likely that a few may have been very lucky and were able to survive. This postulation makes it possible - even plausible - that there could be Kindred of ANY generation as much as 8,000 years old or more. Though the further you go back, the less likely they managed to survive this long.

One clue to this possibility is the existence of the so-called 'ghoul families' of eastern Europe. These families are said to have arisen from ghouls, but are now independent of the ghouls' need for a constant resupply of kindred vitae. No adequate explanation is given as to how or why these families of 'ghouls' are capable of existing independently, or of breeding true and producing ghoul-like children. Nor is any explanation given as to why they age from infancy to adulthood and beyond.
But - if one assumes the appellation of 'ghoul' is a mistaken one, and that these families are in fact derived from an earlier occurrence of groupings of 15th and 16th generation Kindred - now being called 'dhampir' - then suddenly all of this begins to make sense. The thin-blooded high generations closely resemble ghouls in many respects, and are able to breed as if human. A long term breeding program mixing mortals and these generations might produce such independent ghoul-like creatures as are represented by these 'ghoul families'. In fact, such a breeding program is hinted at in the explanation of these creatures - but it is assumed that the program was started with ghouls, not Kindred.

It may be difficult to see the point in this writing. Who would want to bring a 2,250 year old 13th generation vampire into a story, after all? The 13th generation are inherently weaker than the lower generations, aren't they? Perhaps on the surface, they are. But consider a 13th generation kindred that has had over 2,000 years to perfect their Disciplines and Skills. They could conceivably be at maximum in almost everything they possess - and that could mean a whole slew of Disciplines over and above what is expected by Clan. Generation alone is anything but the deciding factor for the capability and threat a Kindred presents - age is far more a relevant scale to measure by, and as you can see by this explanation here - age could very well be unlimited.

The table that follows here is a short summary of Kindred prehistory that I have assembled combining myth, religious belief, White Wolf clues, and actual historical and archeological evidence.

It might be interesting to note - if these assumptions are at all true - that each of the cities from first to third lasted only about half the time of the one before it before falling to destruction.