Fair point, but there are far more humane ways to act then execution. They could simply demote them, but death is not the answer in a situation like this.

What is the source for this, and how was this event documented?

Silk Road Merchant: Due to the mongols having so much power over land, the Mongol Empire led way for a revived silk road

Silk Road Merchant: Due to its safety, many people, such as Marco Polo, could make their way from one end all the way to the other.

Silk Road Merchant: Made silk road relatively safe due to the peace existing in the Mongol empire, as the Silk Road was not as safe before.

The Mongol Empire did not last more than 80 years, resulting in a very short impact.

If warriors did not follow moral code, they would be executed.

Spreaders of the plague, causing for lots of unnecessary deaths.

The Mongols had created the best organized army in the world. Therefore, they ere very dominant when they went into battle.

The Mongols practiced religious tolerance, therefore meaning they were not discrimatory towards religion.