I don't think you can point and click at an obvious candidate as leader of the 'Scandinavian' civilization. And please remember, we're not talking about nations or rulers per se. We're talking about warlords and occupied/sacked territory.
Civilization(the game) as a concept is not about established rule, but the tools to actually establish a rule at any given time in our history. The germanic tribes that occupies roughly todays area called Germany is known as the foot that stomped the Romans. They where uncontested at their time, and where a domintant force in the whole of the region. But the unique unit is the Panzer, a weapon of Adolf Hitler's 'Blitzwar' machinery, not the barbaric germanic tribesmen or Frederiks Ironclads. Zulu warriors where unmatched in their region at the time, and they actually withstood and sacked some of the colonial forces with their vastly superior firepower and technology.
The vikings where a very strange lot by the loose connection between the homeland and the invading/exploring parties. They had no 'Praetors' who reported back to the ruling forces in the homelands. Much of Viking 'expansion' happened by a mutual assimilation of cultures wherever they landed for a period of time. The forces who sacked/tried to sack Byzantium repeatedly in the 9. and 10. centurey where not exactly true blood Vikings, but their technology and mythology where absolutely viking in origin. And they had the tools to shake established empires with large wooden canoes and small ships and sneak attacks down the major waterways of central/east europe.
I think Canute is a good enough ruler as any other. Yes, another choice Margarete I, as would Harald Hårfagre have been. All three come from each region of the three scandinavian countries of today at different times. The idea of the Vikings are the essential message here, not the various leaders.
Dhengis Khan didn't care about rulership. His technology paved the way for him in an unpresedented path of warfare in our world history. He's an undistributed figurehead of the Mongols, but not ruler of any magnitude. And you can hardly claim that Mongolia has dominated the era from 4000BC until today.
I think Canute is the closest thing to a Viking leader that first ruled most of what's todays scandinavia. So he's a natural first choise. George Washington could've been America's ruler, but we're stuck with good ole Abe. So there's plenty of historical opportunities or reasons to choose different leaders than the ones Sid and his team choose in the end for the game.
If it really bothers you so much, you can change the art files to get a proper leader. I think Ragnar is cute, so I'll keep him.
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Sorry for incoherent sentences. I'm dead tired and bored at work...
