"Estimates suggest the Mongol Empire, under Genghis Khan and his successors, killed approximately 40 million people during their 13th and 14th-century conquests. These invasions, spanning 22% of Earth's land, depopulated massive regions and caused total casualties, including significant losses in Persia and China, such as two to fifteen million during the Khwarazmian conquest."
Even worse, a war 200 years ago only in China that killed almost as many as WW2
"The Taiping Rebellion (1850–1864) is considered the deadliest war in Chinese history and one of the deadliest in world history, with estimated deaths between 20 and 30 million, potentially reaching 70 million due to related famine and disease."
As for the middle east, including Iran etc, its been in a constant state of war for 5000 years.
War is the one thing that all humans do and will default to.
Of the 10 deadliest wars by death toll, excluding the world wars as they were pretty much everyone, the only ones involving European were the Spanish conquests of the Americas, the rest is all Chinese and one Timurids (Afghan/Iranians).