A man walks by a house that was damaged during clashes in the Tartar district bordering the Nagorno-Karabakh region, on Sept. 29, 2020. Credit - Tofik Babayev—Xinhua/Getty Images Intense fighting has erupted in Nagorno-Karabakh, a small enclave in the southern Caucasus mountains, setting the entire region on edge. This is a fight primarily between Armenia and Azerbaijan, two former Soviet republics with long-held grievances over land, but the involvement of Russia, Turkey, and others raises the stakes for where a war might be headed. In essence, this is a story of a powerful outsider changing history by drawing arbitrary lines...