Sigbjörn, of the House of Gute, inherits both the Fylkirate and Empire of Scandinavia at the young age of 16. Having wisely adopted both Feudalism and Primogeniture, his grandfather ensured that Sigbjörn's inheritences were kept fully intact... Although growing pains from the early adoption of feudalism are still apparent in the Empire, Sigbjörn weilds a signifcant amount of power, on par with that of the Germanic kings in the British Isles, and even that of the Christian kings on the mainland. The realm is stable, and constant raiding is no longer as economically crucial. Thus, macro-politcal concerns take the forefront. Sigbjörn's life consists mainly of participation in the Germanic conquest of Britannia abroad, and battling the Karling dynasty's obsession with the Duchy of Holstein at home.
Under the leadership of Fylkir Sigbjörn 'the Holy', the Reformed Germanic religion becomes ascendant....while the Church of Rome falls into ruin. Britannia falls under entirely Germanic rule. Irland remains the staunchest of allies. In time, all of the Norse petty kings, and even the mighty Jomsvikings, fall under the rule of Fylkir Sigbjörn 'the Holy'.

"Things are going well!", thought Sigbjörn one day. Things were not going well. You see, somewhere along the way, Sigbjörn had gone stark raving mad. After enacting several absurd laws and decrees, Sigbjörn fully crossed the Ruibcon of lunacy, appointing a horse as Court Physician. Of course, nothing but the very best would do for such a magnificent steed, so Sigbjörn decided that his most trusted Advisor should also be granted many honors and concubines... Several dozen times in his life, Sigbjörn had been visited by strange merchants from a place called Hindustan, who always seemed to want to leave behind gelded slaves; Even the horse thought it was weird. One night, while deep in conversation about the seemingly endless influx of Hindustani castrators into Scandinavia, Sigbjörn and his steed hatched a plan to lead an army east. "But what route shall we take, my most trusted advisor?" The horse seemed to indicate that taking either Eliat or Sinai in a coastal conquest was the only way through. "Then, the county could be granted to our vassal Trade Republic, and we'd have an ample amount of ships to carry our troops east!" Of course, this was a stupid plan, thought up by a stupid, stupid horse. "Oh yes, let us do battle with the Sunni Caliph, in his own desert, all while being out-numbered at over 2 to 1... You are starting to sound like a Catholic!"

The next morning, suffering from a horrific hangover, Sigbjörn's horse was awoken by the thundering sound the Emperor's retinue, and the entire host of Jomsvikings, all lining up to board the vassal navy. (*cue music*)
Sigbjörn proudly proclaims, "Thor has shown me the way, my steed! You know, Thor? The fishmonger that married my cousin? Any road, prepare for untold glory!" And so it came to pass that Fylkir Sigbjörn 'the Holy', accompanied by his mighty steed, did take their fleet through a labyrinth of rivers, all the way to the Caspian Sea. And then did make landfall... Crossed the mountains... And the desert... Into India... Down the long coast... To the penultimate moment, where Sigbjörn first laid eyes on the Kingdom of Lanka.

All told, around 1500 warriors died along the way (even with full reinforcement). This put Sigbjörn's host at a numerical disadvantage. To ensure he wouldn't have to fight a costly battle across the strait, Sigbjörn waited until exactly one day before arriving in Lanka to declare a county conquest on their capital.
Despite their inferior numbers, Sigbjörn's army had the element of surprise. More importantly, the Jomsvikings' shock troops, Sigbjörn's own defensive retinues, and the northmen's superior commanders all combined to tell a clear-cut tale of quality vs. quantity: The war was over before it had begun.

After numerous one-sided battles (and 75% Warscore), the siege begins.
All the mundanity of a protacted siege now follows...
Sigbjörn gets a pet cat.

It fights with his pet dog.

His dog runs away.

His horse and Spymaster give birth to a son.


This kid is going places.

Anyway... The army of Lanka makes one last ditch effort, but it's completely pointle-

Of course he was...

Nonetheless, the war is soon over... Or is it?

Even at 100% Moral Authority, converting this province is going to take awhile... Best to finish this sooner than later.

"What's five thousand prestige to a Fylkir like me?" - Vikings in Paris (feat. Kjeldne Westsson)

Curses!

Rinse.

Wash.

Repeat.

Sigbjörn captured the whole of Lanka in one fell swoop, and it only cost 7800 prestige! Give the man a hand?

"The art of being Fylkir, my beloved horse, is much about doing things in the correct order." - Fylkir Sigbjörn, right before putting his boots on before his pants.
Before you do this...

Do this. You'll be glad you did later (unless, of course, you like pushing legalism a second time for no reason)

But, while you are doing both (and this is where the Agnatic Primogenture comes in), give your heir as many titles and vassals as possible (minus the Fylkirate and Jomsvikings, of course). Also, give them a county in Lanka: This way, combined with your retinues, you will be able to defend against any Dharmic rulers that attempt to go after Lanka.
While you are at it, take that ever-so-useful Titular Duchy you have access to (Duchy of Visby), and use it to create a Trade Republic in Lanka: It won't pay off for awhile, but it'll be a giant piggy bank in the future. Now, onto the white elephant in the room: Getting rid of the Empire title:

1) Switch the succession to Elective Monarchy.

2) Elect a non-dynasty member

3) Make your horse and Spymaster's half-breed of an abomination son a powerful Duke (you want the incoming Emperor to have as little power as possible, might as well do it with style)

May he reign a thousand years, neigh?

4) Die.

At this point, you have lost the Empire, but kept all your kingdoms, retinues, items, and gold. You also kept the Jomsvikings as your vassals. Long story short, you are more powerful than the Emperor, so get ready to declare independence. The first thing you want to do is go get your retinues from Lanka, hopefully you have a commander with the organizer trait...
Well, that worked out... Next, sail your retinues to the Duchy of Sinai, and another fleet south to meet them:

Just a horse leading a bunch of vikings north to the Mediterranean, Mr. Caliph, nothing to see here...

When you are ready, declare war against the Emperor for independence. You should win easily.

Now that you have thoroughly disrespected the legacy of the Great Fylkir Sigbjörn 'the Holy', and your dynasty as a whole, you probably feel like running away to India, never to return. I don't blame you, you filthy wretch.

Neither do these guys...

Yeah, that's what I thought...

The powerful legacy of the Germanic faith (desipte your best efforts) remains, and you are still the Fylkir. The very least you could do is divide up your ancestral lands in the most beneficial way possible, setting up your dynasty members as powerful kings. I mean, you can still call Great Holy Wars every 30 years, that sounds fun, right?

Something like this. Bonus points if you can give powerful non-dejure jarls (i.e. dukes) kingdoms adjacent to their lands, and give the heirs to kingdoms a kingdom of their own (again, the raw OP power of Agnatic Primogenture cannot be understated here)...

You have dismantled the Empire your ancestors built. You have taken away the Jomsvikings and the Fylkirate, the most powerful weapons your people have, forever. And for what? GG

Now, the point of fully withdrawing to India is that cultural conversion can take a long, long time. With less to do, you can ride it out at 5x game speed. On the bright side, it's almost impossible to screw up at this point.

You have your defensive retinue stack, the Jomsvikings, and Agnatic Primogenture: You have never been safer in CK2. So, set Crown Focus to your capital, set your Steward to "Administer Realm", smash that 5x turn speed, and get ready to stare at this for awhile:

Time passes. With the Fylkir and Jomsvikings missing in action, life goes on in the Germanic world (as if you care, you achievement-mongering son of a goat-herd).

The realms united according to plan, and the Germanic kings continue to gain ground. But let's be honest, what we really care about at this point is the horse...

...at least he died doing what he loved...

...and founded a great dynasty. His son, Jarl Bu-Ceph 'the Horseman', sires many sons...

May he ride with Sigbjörn in Valhalla. Meanwhile, in Lanka...

Eventually, either the culture will convert normally, or this will happen:

Make it so.

And there it is, your reward for all this Fylkiry:

(*cue credits*)