Firstly, Vikings is good fun to watch. Plenty of great action, generally good production values etc. I've watched every episode, and I am not going to stop.
Sure we have seen frontal cavalry charges against heavy infantry (not done by anyone), women "shield maiden" fighters in shock combat (there is literally not an iota of evidence that ever took place). Even if the girl power stuff is fiction I get that, it is done to attract a female audience.
But the depictions in Kievan Rus are not just a bitin season six are not a bit off the mark, but thousands of miles and a 100 years off the mark. But unlike female warriors, or fighting without helmets (done so audience recognize characters), one has to ask what is the purpose of the grossly wrong depictions in Kievan Rus? why are the warriors there wearing Mongol style clothes??? The populations there in Ukraine, Belorus and certainly western Russia, would have been a predominant population of Slavs, and a ruling class of of Nordics, specifically vikings, who had come down the rivers with advanced fighting skills, river capable long boats, and become the ruling elite class. Ok the trader from Samarkand maybe, but Oelg's fighters and population? No.
and why is Oleg calling Ivar an "Varangian", the byzantine Greek name for riparian (river) vikings inhabiting area of Ukraine, when Oleg, Dir and and Askold were themselves were definitive Varangians??
Also what is with the litter Ivar is in and the road travel? those areas the transport was by river and the viking long ships where a key part of the trade, which was predominately north south along the Dniester, Dniester, Don and Volga.
Again the anachronisms and major and minor history errors in seasons of the past have explanations/excuses/valid reasons -- what we are seeing in season six has no reason to be so inaccurate.