"By establishing strong "fair" law they stopped long lasted inner-conflicts and "made life better"." They established fair law for 80 years at most, and at the

"By establishing strong "fair" law they stopped long lasted inner-conflicts and "made life better"." They established fair law for 80 years at most, and at the price of killing off a substantial percentage of the peasantry (who the Mongols, as pastoralists, viewed individually as less valuable than a horse) of conquered regions. In Iran, the depopulation led to the underground irrigation system, known as the qanats, falling into disrepair, which led to formerly productive agricultural lands drying up, and the region regressing from agriculture to pastoralism. In the absence of a productive countryside, some of the largest cities never recovered until the 20th century.