Pax Mongolica, which means Mongol Peace in Latin, is a historiographical term describing the stabilizing effects of the Mongol Empire in the vast Eurasian territory that the Mongols conquered in the 13th and 14th centuries CE.

Pax Mongolica helped the development of commerce and communication in the region, especially along the Silk Road, and helped make possible the formation of closer ties between the Eastern world and the Western world.

The Mongol Empire developed a reputation for fiercely guarding the Silk Road to ensure its usefulness for travelers. In contemporary sources, it is not usual to find (probably a tad hyperbole*) claims of how “a maiden carrying a nugget of gold on her head could wander safely throughout the realm”.

Source: http://www.silk-road.com/artl/paxmongolica.shtml

*See an English teacher to explain hyperbole, but basically it's an exaggeration