No one has mentioned the HRE yet, not sure if that counts here though. The Holy Roman Empire was a collection of very small states, grouped together under one Emperor, and was of the same size roughly as France throughout the 12-1400s, maybe even bigger. However, the fact it was divided and had in fighting for the position of Emperor probably weakens it a fair bit.
Poland-Lithuania was huge in this time period, as was Hungry. You might want to also look at Sweden, as they were pretty damn big.
Further east you have islam, where things get a little muddy.
http://countryturkmenistan.tripod.com/SeljukEmpireMap-resized.jpg That thing is pretty big

The Seljuq's ruled an empire that went from as far east as the kush mountains, to the Mediterranean, but maybe were at their peak a little before the dates you have set.
You also have to notice the caliphate, although not a truly unified state, was the muslim rule of all nations from north africa, again up to modern day iran, afghanistan and pakistan. I think at this time it was the abbasid dynasty.
But yeah, as others have said, this question is far too vague. Firstly, what do you mean by power, and secondly, a nation is kinda tricky to define in this period where so many different forms of rule existed.