How to Win a Cultural Victory as the Danes

When you start, you are vunerable, and exposed, and have few friends. You should first make peace with the Rugians, and that might take a little money, but hey, it is better than them invading you. Now there are still those Vararians to the south, however, don't bother with them, as they are wiped out by the Bungundrians rather swiftly. Now you are going to build up your army. Get lots of trade with you neighbors in the Baltic. Build a strong navy. Your strength is in naval affairs.

With you new armies and fleets, attack the Jutes. Declaring war on them would not only unite all Denmark under you just rule, but would also plese the Romans, who cities thay have been burning. So while the Jutes are raiding Roman cities, they will probably taken by suprise. Loo their capital, Alabu. The Jutes will probably migrate to somewhere in France or Britian. I made the mistake of hunting them down. Let Rome deal with them. Instead, now is a good time to build up your power in the Baltic. Colonize Duna, that little uninhabited settlement along the Baltic coast. In Hafn, build a chieftain's house, and upgrade the building whenever you get the chance.

You should now have lots of trade, have a strong foothold in the Baltic region, and have a decent army and navy. Now you should use your armies and fleets to launch a naval invasion of Britian. Looting Britian help fill your treasury. It is up to you whether you would should rule Britian directly, or force the existing rulers to become your tributary states.

In this game, most of what is now Russia and Kazakhstan is desolate. Colonize as much as many of these regions as you can. Go all the way down to Sycthia. They have little resources and few are interested in them, but they will all add up as regions for your victory conditions. Meanwhile, across the Caspian Sea, there lies the Sassasind Empire. The Sassasind King of Kings has some trouble with his rebbeling Staraps. The King of Kings will happily accpect your help. This lets you get a few regions in the Middle East.
These regions can be very valuable. For expample, the city I took, Ebacanta, had a silk road trading post. As High King of the Danes, look far beyond your homeland, just like the Vikings did historically.

At this point, the your faction should look something like one of these:

Make sure you meet all the victory conditions for cultural victory and watch out for those Huns. They could eaisly ruin everything. Don't really trust the Germanic tribes either.

Make as as many trade agreements as you can, and use the easy diplomacy mod to make it easier. On marketplaces, I strongly advise you build ones that sell food. They provide food, so not only will these make you money, but they will also feed your people. The slave marketplaces are not very useful unless you are a horde, and the jewelry marketplaces are good, but still are not as cool as the ones that sell food.

Chose your heir carefully. Try to keep your family's balance of power right in the dead center; when you get too weak, your generals and bureaucrats will constanly take advantage of you and look for any weakness and attempt to seize power in a civil war, while being to powerful will cause your people, generals, and bureaucrats to distrust, fear, and even hate you, which could lead to revolts. Being moderately powerful earns the trust of your generals, bureaucrats, and people. I learned the "don't get too weak part" the hard way when I got in a civil war, but luckily, the seperatists did not even last a turn. Arrange lots of marriges for the sake of diplomacy. Don't be afraid to assassinate your High King if he is undesirable. Lastly, use the political actions when you need them.

For the settlements in Scandza, I advise you go down these building chains:
Hafn:
Trading port
Government
Religious (Burial building)
Alabu:
Trading/fishing port
Goats
Sanitation
Herfnesholt:
Mitilary Port
Lumber
Mead Hall
Food Marketplace
Storehouse

If you max out all the building chains, this should be your final result:

For all your other settlements, I do have a few tips:
-Improve upon resources whenever you can.
-Don't blindly upgrade the settlement, as that can lead to food sortages.
-Try to build food marketplaces in major settlemets.