What follows is Ralf’s Reply to the question: "The story line:how do all might and magics go together?" posted by Lazygamer on May 12, 2000 at 12:41:06:

The missing link is that HoMM I doesn't have a very detailed back-story. But, if you read the letters in the correspondence that appears in the back of the manual, and construct a fuller history of 1-5, you'll notice a connection. Also, there is a MAJOR link between MM III and MM VII

Here's the whole thing:

Corak is either an Ancient, or a constructed servant of the Ancients. We really don't know who or what the ancients are yet, but judging by the GOOD ending to MM VII, we are on the threshold of finding out.

Now, the Ancients used to spend a lot of time "seeding" the galaxy with microcosms –– small biospheres supporting life. In fact, in the first 5 MM's, all the planets are flat, and in fact are strategically placed life support systems. We don't know why they did this.

About 900 years ago (if my memory of MMVII serves me) the ancients got in a horrible war with a race called the Kreegan. A large part of the galaxy was cut off from the direct influence of the Ancients, and fell into barabrism and
witchcraft. In fact, these isolated worlds are precisely the worlds in which the MM games occur.

Many of these worlds had "guardians", appointed agents of the Ancients who were sent to guide the microcosmic little flat planets to their appointed place in the galaxy.

Now then.... as the story begins, Sheltem, the Guardian of Terra has gone funny in the head.
As we eventually find out from logs in the shuttles in MM V, Terra was a large, hospitable planet, which the Ancients were intending to seed with numerous of these microcosms.
Apparently, the Ancients weren't too happy with the way he was running things (he became a bit of tyrant it seems), so they dispatched agent Corak to check things out. Corak placed Sheltem in stasis and was bringing him home to
check his programming.

Somehow, Sheltem escapes and goes on a rampage. Corak begins his long quest to track him down and neutralize him.
As the story opens in MM I, Sheltem goes to ground on one of these microcosms named VARN.
This is an acronym for something, which I cannot recall. He deposes the good King Alamar and masquerades in his place. Our party of adventurers discovers him and sets everything to rights. Sheltem flees to Cron via a gateway
which we will see more of in MMVII. It should be noted that there is a location in MM I called Castle White Wolf. The Lord of this Castle is named IRONFIST, and one of his quests is to find LORD KILBURN. Remember those names for about 6 paragraphs.

In MMII, Sheltem winds up on Cron and starts to drive it off course and hurl it into it's sun.
With a little help from Corak in stasis, our heroes manage to thwart this scheme as well.
However, Sheltem escapes as we are busy decrypting a quote that will give us the password to the device and stop Cron from commiting sun-icide.

Next, in MMIII, Sheltem arrives back on Terra which is where the whole mess started.
Again, our trusty adventurers find out what's going on behind the scenes and drive Sheltem off. Three space shuttles depart Terra. One containing Sheltem, another containing Corak in pursuit, and another containing our party of adventurers. Something happens on this journey. Sheltem lands safely on XEEN.
Corak lands much less safely on XEEN, and our adventurers are thrown off course, supposedly never to be seen again.... at least, not until MM VII.

MM IV (Clouds of XEEN) opens on XEEN, and our new party of adventurers defeats an evil undead lord calling himself simply, "Lord Xeen".
As we defeat Lord Xeen, we see a vision of Sheltem proclaiming, "You may have defeated my lieutenant, but the Darkside of Xeen will always be mine. BWAHAHAHAHAHAHA!!!!!!"

MM V opens. Sheltem is up to his old tricks, masquerading as Alamar again and driving planets off course to fly into their suns. The dragon pharoah summons our party and they perform many tasks to set things to right. Eventually, they discover Corak's shuttle, and the stage is set for the final showdown of Corak and Sheltem. You seek out a "soul box", a device which can contain Corak's essence so that you can smuggle him into Castle Alamar without Sheltem being aware. Once you arrive, you release Corak, and he finally has a chance to confront Sheltem face to face. It is obvious that Sheltem has grown very strong "in the ways of the force" and is going to win this battle.... but Corak grabs Sheltem and initiates his own self-destruct mechanism, destroying them both. So ends the
first story arc in the Might and Magic pantheon.

(The extended 'World of Xeen' ending doesn't figure into the grand scheme too much, so I won't comment on it here.)

Next up would be HoMMI. Per the letters, someone apparently named Morglin Ironfist was involved in a power struggle on his home planet and his lineage was usurped by his cousin. Morglin failed to make a successful coup and therefore ran for his life with a small retinue that was loyal to his line. There are a number of hints dropped that this may be the Lord Ironfist from Castle White Wolf on Varn, or perhaps one of his descendants. Note also, that MM VI has one subplot featuring a Lord Kilburn, also named in MM I. And MMI begins in the town of 'Sorpigal',
and MMVI begins in 'New Sorpgial'. Anyway- while on the lam, Morglin Ironfist accidentally trips through a magical portal to another world, Enroth, and sets up his reign there.

HoMM II is the next scene in the story, the succession wars. Morglin's sons, Archibald and Roland have a little tiff over who is going to inherit the throne. It's all family squabbles, nothing hugely important to the overall story. At the end, Roland wins and Archibald is turned to stone and imprisoned in the library of Castle Ironfist.

MM VI picks up again with the big picture, and makes it much bigger. The Kreegan, after 900 years of fighting the Ancients in other parts of the galaxy are finally making a push towards this region. They land in Enroth and in Erathia and start a reign of terror. MMVI takes place in Enroth. Roland is defeated in the opening battles and is captured, not to be seen again in Enroth for a LONG TIME. His wife, Catherine of Erathia has heard of her father's death and has departed for home and doesn't hear of this issue for some time.

Their son, little Nicolai, is left in charge.
Our heroic adventurers are guided by the chief regent on a series of quests to figure out what is going on. Eventually we discover that the evil cult of the temple of Baa are in league with the demonic kreegans and many other adventures are had.... Eventually, the oracle of Enroth is able to tell us how to defeat the Kreegan. We need to free the stoned Archibald!
He has a magic item we need to teleport the Kreegan's nest into the void as we destroy it - in order to avoid destroying the planet as well.
We succeed in defeating the kreegan.

HoMM III follows up from MMVI and largely takes place at the same time. The Kreegan and warlocks have overrun Erathia and made quite a mess of things. Catherine arrives for her father's funeral and discovers that the land has a bit of trouble. She takes up the banner of Erathia and begins a successful campaign to push them back. The warlocks make a pact with the Necromancers to ressurect Catherine's father as a lich and lead the war against Erathia. It's a bloody mess, but eventually Catherine wins the day, lays her father to eternal rest, pushes the Warlocks back to Nighon, and forces the remaining Kreegans to hole up in Eoful.

In all the turmoil, the re-awakened Archibald sneaks into Deyja, the land of Necromancers just north of Erathia, and begins rebuilding his influence in the world.

MM VII opens with the strongest link between the original five games. The shuttle carrying the 8 member party from MM III - which missed XEEN completely - finally crashlands off the coast of Antigarich (the continent which contains Erathia, Eoful, Avlee, Nighon, Bracada, and Tatalia.) At this time, they have a split. 4 of them decide to seek out the wizards of this world and offer them their technology and see if they can rebuild a gate to the ancients.
The other 4 seek out Archibald and the Necromancers and seek to build the Forge- a machine which can grant them extremely powerful weapons to dominate this world. Which group will succeed depends entirely on your party's
actions. Assuming that you choose the "good" path, which is fairly important for the overall story line.... You will finally wipe out the Kreegans, free Roland and indirectly defeat the Necromancer's guild. You will also succeed in
building a gate which takes you to an interstellar waypoint, where you meet someone named "Corak", though not the same "Corak" of MM's I-V. Corak gives you some information about the Kreegans and the Ancients, and answers the question, "Where can we go from here" with, "Anywhere you want to!".

MMVIII opens. Apparently, we were a little too slow to defeat the Kreegan menace. Someone among the ancients seems to have a "Scorched Earth" policy. That is- do NOT let the kreegans have a planet under any circumstances. If the locals can't defeat the Kreegans, destroy the planet. The planeswalker, Escaton, who appears to be another automaton like the original Corak, is dispatched to destroy our planet. He appears in the third continent on this world, Jadame, and opens portals to the 4 elemental planes.
Once their energies leak into the world, and meet at a certain magical crystal... POP goes the world. Our heroes are tasked with the monumental project of building an alliance among the races of Jadame and closing the planes.
Along the way, we discover that the order was given before we finally defeated the last of the Kreegan in MMVII, but that Escaton is unable to avert his programming and stop the process.
Roland and Catherine make an important cameo appearance as they stop in Jadame on their journey from Erathia back to Enroth.

At the end of MMVIII, The Ironfist Dynasty is back on track and the Kreegan (and all of their side effects) are finally beaten down.

Also, we have the Gateway from MMVII opend for the first time in many centuries.

My guess is that MM IX will draw us directly into the Kreegan/Ancient war.

That's my story and I'm sticking to it.