Homosexual acts were punishable by death under Genghis Khan’s rule, according to researchers who have spent over a year compiling the legendary Mongolian conqueror’s code of laws.

Xinhua News Agency has reported today that article 48 of what is believed to be the world’s first constitution said men who “committed sodomy shall be put to death,” according to Chinese researchers.

Genghis Khan’s code of laws is one of the earliest to have banned homosexuality in Central Asia.

The experts at the Research Institute of Ancient Mongolian Laws and Sociology said the ban was put into place because Genghis Khan wanted to expand the Mongolian population, which was about 1.5 million at the time.

The rival Song Dynasty, which dominated today’s central China, was 100 million strong, Xinhua said.

Khan’s 13th century empire stretched across Asia all the way to central Europe.

Experts compiled the Mongolian code based on historical texts, including Marco Polo’s travelogue, Xinhua said. The original text was lost more than 600 years ago.

“Genghis Khan’s Code”, published by the Beijing-based Commercial Press, contains Chinese and English versions of the code as well as interpretations of the laws based on research findings.

Genghis Khan, whose grandson Kublai Khan founded the Yuan Dynasty (1271-1368), unified Mongol tribes and conquered most of Eurasia.