I thought it was just that the Autobots and Decepticons became Maximals and Predacons DURING the great war (in the 300 some-odd year between the arrival on Earth and the start of Beasts Wars.) not that they made peace, upgraded, and then started a new war.
BW is VERY vague about it.
IIRC, we are told:
The Great War ended.
300 Years latter is the Maximal ruled Cybertron of the BW Present.
We are not told:
When the Great War ended (2005? 2023? 4333?)
What planets "Years " we talking about? Cybertrons?
And then latter fiction added the caveat few probably had even thought of "What if they were talking about an entirely different 'Great War' than we were thinking."
-ZacWilliam, they really should have called it Great War II then, even we dumb humans figured that out.
Actually original intent was that the Great War mentioned was a War between Maximal and Predacons; but since it was vague; Fans all assumed it was talking about Autobots and Decepticons; and the writers went "sure, why not?" and ran with that instead.
And this is why the history between the Autobot/Decepticon era and the Maximals/Predacon era is such a vague mess.
The first episode made mention of an event called the "Great War". Bob Forward originally didn't intend for it to mean much beyond "some conflict happened in the past and that's why the Maximals and Predacons presently don't like each other." But then the fandom latched onto the idea of it referring to the Autobot/Decepticon war of G1, and so Forward and DiTillio leaned into that notion, making it official in all references to the "Great War" in the rest of Beast Wars, and even its one mention in Beast Machines.
The first episode even had Optimus say "There has been peace between the Maximals and Predacons for centuries." Combined with the show cementing the Great War as referring to the Autobot/Decepticon war, the idea that there was ever a war between between the Maximals and Predacons (let alone one that was
also called the "Great War") is pretty antithetical to the show's intent.
Yet, circa 2005-2009, Ben Yee was given the lucky opportunity to write/co-write some Beast Wars fiction for both Fun Pub and IDW, in which he invented the idea of there having been a
separate "Great War" fought between the Maximals and Predacons in the years before Megatron stole the Golden Disk. Specifically, the BotCon 2005 Deathsaurus toy bio, Optimus and Megatron's BotCon 2006 toy bios and their extended "Dawn of Future's Past" profiles, the Fun Pub prose story "The Razor's Edge", the Beast Wars Sourcebook, and the BotCon 2009 Razorclaw toy bios all provided details about this war, and even made Optimus and Megatron veterans of this war (which is just
nuts).
As for the exact time between the Autobot/Decepticon age and the Maximal/Predacon age, two official timeframes were given between Beast Wars and Beast Machines. The first was in the Beast Wars episode "Dark Designs", in which Blackarachnia said about the Decepticon Shrapnel, "That was a Decepticon from the Great Wars three centuries ago!" This "three centuries" claim is the most commonly known one, the one that most Beast Wars tie-in material from BotCon and IDW have run with... and the one that honestly makes the least amount of sense. We're talking about a race that can live for
millions of years, and yet after a measly three centuries do the Autobots and Decepticons go completely extinct and fade into the realm of myth and legend?
And, yes, they
were regarded as such by the Maximals and Predacons. The episode "Possession" first established that the 'Bots and 'Cons were not only the "ancestors" of the Maxies and Preds, but specifically their "
ancient ancestors". Something "ancient" for a millions-of-years-old people ought to be well over a few centuries old, which brings me the other timeframe, the one given in Beast Machines. In the episode "Sparkwar Pt. II: The Search", Nightscream says of the ancient Autobot city of Iacon, "This city was lost
eons ago after the Great War between the Autobots and the Decepticons." That's right, he said "eons ago", which is much more in line with how far removed from the Autobots and Decepticons the Beast Wars and Beast Machines cartoons intended the Maximal and Predacons to be.
When Starscream first showed up in "Possession", the only ones who had ever heard of him (one of the most
infamous Decepticons of all time, no less) were Optimus, Dinobot, and Blackarachnia. When Blackarachnia and Silverbolt find the Ark in "The Agenda (Part III)", Silverbolt admits that he thought the Ark was only a legend. Over in Beast Machines, Vector Sigma is confirmed to have evolved into the Oracle at some point in the past, but by the first episode, everyone only remembers the computer by its "Oracle" name and were convinced that its existence was "just a legend." In "The Key", Tankor-Rhinox asks Optimus if he's ever heard of the Key to Vector Sigma, to which Optimus says is just "An old Autobot legend." In "End of the Line", when Megatron hears about Optimus having found the Plasma Energy Chamber, Megatron is in disbelief, yelling "The Plasma Energy Chamber is only a legend!" Even in the Beast Wars production bible, it states that the Maximals' and Predacons' knowledge of their having been descended from the Autobots and Decepticons originates from "Cybertron Mythology".
And a big one that the fandom completely overlooked is the fact that Ravage's reconstruction from Decepticon to Predacon, and his continued existence in the Max/Pred age, was known only as a
rumor! This even suggests that the whole notion of the Autobots and Decepticons being downsized into Maximals and Predacons was never an intention by the cartoon itself, and the very concept even originated from
outside of the show (
see the Notes section of this page, starting with the second bullet point, for more).
And yet, as I said, the "three centuries" claim is the one that got noticed more and was ultimately used by both BotCon and IDW, allowing both to narrow the gap between G1 and Beast Wars in their own ways, all to inject more G1 into Beast Wars instead of allowing Beast Wars to stand tall on its own original lore and merits.