The Pax Mongolica is a term used for the period of Mongol rule during the 13th and 14th centuries, where there was peace on the vast territory that the Mongols controlled.
Once the Mongols established their empire, they rushed to do some reforms, and one of those was the security issue, especially alongside the Silk Road. The Mongols managed to control the situation for some time, and there was peace, even in the Eurasian steppe, a place well known for constant battles between numerous people. Lot of people, especially traders and merchants wrote that during the Mongol rule, a person can go on foot from Europe to China with a gold on his forehead, and not be afraid for his safety.