The term “Scorched Earth” was first manifested in the final days of World War II. As the Russians were forcing the Nazis to retreat pushing them further and further back into Germany,they made sure that the Russians could not use anything the Nazis abandoned in retreat, against them. And so enforced a scorched Earth policy where everything left behind was utterly, totally destroyed as not to give the Russians the slightest military advantage.Thus, Scorched Earth.
With race riots cities burn, same thing, burn it all down.