There have been cases in the past where an external strong power has been able to suppress both sides but it has to be done for generations until the reasons are lost to time.
Depending on who you ask, there have been a variety of external powers stirring the pot. Most people are horrified by the violence. Beyond the territorial, religious and cultural disputes there are opposing geopolitical factions.
Of course it is understandable to be outraged by the violence and atrocities. The human suffering is real, but arguments focusing on these points can miss the larger picture. The underlying incentives dictate outcomes. Atrocities are often marketed as rationalizations for further violence.
We want to prescribe an outcome without atrocities. Yet discussions fall into recrimination before they can describe the conflict coherently.