The Yassa laws were the laws of the Mongol Empire under the rule of Genghis Khan. After Genghis Khan died, the laws were still enforced, however it is unclear how strictly and to what extent. The Yassa are also referred to as
Genghis Khan's laws.
You can read more about the Yassa laws here:
Genghis Khan's lawsThe Yassa were based around obedience to Genghis Khan, a uniting together of the Mongol nomad clans, and the strict punishment of wrongdoing.
The Yassa laws prescribed the death penalty for things like
homosexuality, adultery, spying on the Mongol Empire, stealing a horse, and unlawful pillaging.