But there was no such thing as “Viking culture” it was just Piracy. Just an illegal occupation.
But this is exactly what you are asking. Every day we know more accurately what happened in the Middle Ages, the period is, right now, at it’s most popular.
It is better to be accurate, and teach real History. Viking was just Pirate in Old Norse.
Like, half of google page 1 begs to differ. 
But anyhow, I don’t think we’ll agree, as you’re very deeply attached to recently invented semantics and redefinitions, while I am not. So we will simply have to agree to disagree, I suppose.
So according to you, any source that mentions viking culture is not real history. Ah, yeah, I think that discards just about the majority of anything ever written about the subject.
Real History disagrees with it.
Viking is just pirate, not a culture, unless you are advocating that the game should have a Bandits civ, and a Lawyers civ, both of which amount to the same thing as Viking.
This gets into a problem we have now. It’s a linguistic one.
There are 2 definitions of Scandinavia. One is the Geographic Peninsula specifically. The 2nd definition is also geographical but refers to the land of beyond just the peninsula, into even Finland, Denmark, and even Iceland.
The problem with Scandinavia is because it’s more confusing to use.
Norse is better, in my opinion due to it’s blunt cultural implication, but it’s also way more simple. Most people know that Norse basically means Viking in some form or another. Scandinavia is probably way more commonly known but it’s not like you can’t use an unfamiliar term as a civ name for AOE4 (Delhi Sultanate is a name that’s rather foreign to more people than you realize).
And while we are at it, let’s just call the Japanese when they come out NINJA because that is so cool. Even though there is no historical basis for how they are depicted in Hollywood but the “coolness” argument seems to be more important.
You can do the same as Burmese, Siam, Khmer are practically the same ppl in different countries.
“Vikings” is a very hype name for PR campaign and attracting a new players
That is true. So is the word “knight” but I don’t see anyone wanting a “Knights” faction.why do you think that is?
It seems that you cnahged the name of the article? there is no reason to get so agressive.
Because nobody associates “knights” with every European like they do with Vikings and Scandinavians.
But is that actually true? What is the first thing that comes to your mind when hearing the word knight? Probably a European knight on a horse with shining armor right? Even if you don’t think about the whole Europe you are probably thinking about French knights. So if we go by that logic we should call the French faction “Knights”
Don’t forget the Samurai Civilization 
Norse makes the most sense.
Also off topic: Ninja and Samurai were literally the same exact thing, Ninja was just a job that some Samurai were trained to do, but for most of their life they’d just resume being a standard Samurai after that.
Calling any Civ by a warrior name would be stupid. 100%.
Ninja were not Samurai, they were not lordly retainers, but mercenaries with various skills and abilities, that were useful for the daimyo class, but which they did not want to be personally associated with.
It is worthy of note, however, that several dishonoured Samurai, swordsmen schools, and even monasteries, often turned to shinobi work, in order to finance themselves, or make profit from war.
However, the Samurai class were not Ninja themselves, unless they were shamed somehow, and had to seek vengeance through less honourable means.
It is also worth mentioning, that Shinobi were a 15th century phenomenon, that flourished because of Japan’s almost perpetual state of Civil War, and not a wider concept in Japanese society or military culture.
Ninja were mostly just regular spies. Most of them weren’t trained to fight either but rather they would have normal occupations like being a farmer.
They were mostly from the lower classes, and sought to profit from war. Ninja were known for stealing, espionage, sabotage and poisoning people, not actually fighting.
First of all Shinobi were not the same throughout Japan’s history. Same thing with Samurai, who at one point literally comprised 1/10th of the entire population of Japan at one point. That’s how common and low class Samurai could become at one point.
Same thing with Shinobi. Even reading that article, you realize that there is a battle going on. Between the westernized pop culture version, of what later Japanese depicted of the historical Shinobi (which historical documents from the period contradict the post-shinobi depictions of the Japanese) and between the actual historical Shinobi, which were just warriors trained in espionage.
Ninjas as you know them are not as they seem, Wikipedia is where I get my source of that from. Just read through it. While yes, a lot of stereotypical elements of Ninja exist, like examples of the black outfits, the cool weapons, and romanticized “badass clans in the mountains”, it was never like that from the documentation. Those depictions came from later on in Japanese history, and romanticized stories of assassins.
In fact, Ninjas historically have little records of assassinations. They were doing espionage, not assassinations.
Here is even a part where they’re basically saying Samurai became Ninja with even mentioning only once though:
It was not until the 15th century that spies were specially trained for their purpose.[14] It was around this time that the word shinobi appeared to define and clearly identify ninja as a secretive group of agents. Evidence for this can be seen in historical documents, which began to refer to stealthy soldiers as shinobi during the Sengoku period.[22] Later manuals regarding espionage are often grounded in Chinese military strategy, quoting works such as The Art of War by Sun Tzu.[23]
The ninja emerged as mercenaries in the 15th century, where they were recruited as spies, raiders, arsonists and even terrorists. Amongst the samurai, a sense of ritual and decorum was observed, where one was expected to fight or duel openly. Combined with the unrest of the Sengoku period, these factors created a demand for men willing to commit deeds considered disreputable for conventional warriors.[19][2] By the Sengoku period, the shinobi had several roles, including spy (kanchō), scout (teisatsu), surprise attacker (kishu), and agitator (konran).[22] The ninja families were organized into larger guilds, each with their own territories.[24] A system of rank existed. A jōnin (“upper person”) was the highest rank, representing the group and hiring out mercenaries. This is followed by the chūnin (“middle person”), assistants to the jōnin. At the bottom was the genin (“lower person”), field agents drawn from the lower class and assigned to carry out actual missions.[25]
Here is a better source, and they also cite sources for actual historical documentation you can buy and read yourself.
They were actually dark blue, because it melds better into shadows and the night sky, than black.
There were some famous assassination by Ninja, that became famous, the most striking being Uesegi Kenshin getting killed by a man hiding in his toilet with a spear.
It was, however, indeed rare.
Another big misconception is that they and teh Samurai though firearms to be dishonourable, which was far from the truth, and teh Samurai class LOVED gunpowder weapons, specially because they already did most of their killing at range, even before they were introduced.
But what you linked does not say Samurai were ever Ninja, as they could not claim glory for their kills, as Shinobi, so they did not become Shinobi.
The entire Samurai honour system hinged on taking glory from your trophies, and they wanted it to be known when they killed someone important.
Shinobi were from the lower classes, peasants, merchants and monks, more often than not.
id prefer Norse or Danes as the call mark for the “vikings” in game, why?
because the viking age only lasted about 250 years, if even, and a lot of other interesting stuff happened before and after in Scandinavia.
by the end of the medieval period Denmark had gained control over all of Scandinavia in the Kalmar Union, which was 1 of 2 empires Scandinavia made in the period, the other 1 being the North Sea empire, which again was centered around Denmark as the leading dynasty and military.
while obviously the game also should feature real viking units then by age 4 it really should look more like the Kalmar union with halberds, crossbowmen and heavy cavalry.
the definition of scandinavia is pretty simple:
denmark, norway and sweden.
yes the peninsular is just norway and sweden but thats just because it is the largest landmass in the area.
it is also worth noting that we dont know what scandinavia is for certain since the first mention of it is hazzy at best. likelihood is that it is either Zealand or Scania, and not the entire region or peninsular.