Montesquieu

Among them­sel­ves, the Tartars appear gentle and humane, and they are very cruel conque­rors : the city dwel­lers they take are put to the sword ; they consi­der they are sho­wing them mercy when they sell them or dis­tri­bute them to their sol­diers. They have des­troyed Asia from the Indies to the Mediterranean ; all the land that makes up the east of Persia, as a result, remains wil­der­ness.

Here is what seems to me to have pro­du­ced such a law of nations. These peo­ples had no cities ; all their wars began spon­ta­neously and impe­tuously. When they hoped to win, they fought ; when they did not, they went to join the army of those who were stron­ger. With such cus­toms, they found it was coun­ter to their law of nations for a city which could not defend itself against them to stop them. They did not consi­der cities as an assem­bly of inha­bi­tants but as pla­ces ser­ving to evade their autho­rity. They had no art for besie­ging them, and were very expo­sed when they did : they aven­ged in blood all the blood they had just shed.