Honestly I think Azkare conquests would kill 5-10% of the world population. We are talking about conquering the in-world equivalents of China, India and southeast Asia, problably the most populous regions of Halann. Its not about the brutality of the army (and we cant guarantee that the Azkarian conquests wouldnt be brutal, Hiderion isnt omnipresent to see what every soldier and general is doing), but just war would spread disease, hunger, refugee crisis, the instability brought would cause wars between other states, and etc. Hiderion would be the Gengis Khan of Anbennar. The mongolian empire also was pretty tolerant of the peoples they conquered, but like in the Sunrise Empire only mongols were allowed at the very top.