Original sentence: Another serious issue the Armenian Genocide, when actions by the Ottoman Young Turks led to the forced mass evacuation and deaths of an estimated 1,500,000 ethnic Armenians  in what many scholars and countries recognize as the Armenian Genocide
Edited sentence: Another serious issue surrounds the events of 1915–17, when actions by the Ottoman Young Turks led to the forced mass evacuation and related deaths of an estimated 300,000 (according to Ottoman archives) to 600,000 (according to Arnold J.Toynbee, an intelligence officer of the British Foreign Office during World War I), and up to more than 1,000,000 (according to Armenian resources) ethnic Armenians in what many scholars and countries recognise as the Armenian Genocide