The term yasa is a Mongol word meaning "law, order, decree, judgment." As a verb it implied the death sentence as in "some were delivered to the yasa,” usually meaning that an official execution had been carried out. It was once generally accepted that Chinggis Khan had laid down a basic legal code called the Great Yasa during the Great Quriltai of 1206 and written copies of his decrees were kept by the Mongol princes in their treasuries for future consultation. This code, the so-called Great Yasa, was to be binding throughout the lands where Mongol rule prevailed, though strangely the actual texts of the code were to remain taboo in the same way the text of the Altan Debter (an official Mongol chronicle accessible only to Mongol nobles) was treated. This restriction on access to the text explains the fact that no copies of the Great Yasa have ever actually been recorded. Though in reality it never existed in any formal physical sense, in later years many assumed that these collected Mongol edicts known as the Great Yasa had been compiled by Chinggis Khan.
The Great Yasa became a body of laws governing the social and legal behavior of the Mongol tribes and the peoples of those lands that came under their control. Initially it was based on Mongol traditions, customary law, and precedent, but it was never rigid, and it was always open to very flexible and liberal interpretation and quite able to adapt, adopt, and absorb other legal systems. Speaking of the yasas, the Muslim Juwayni
(died 1282), historian and governor of Baghdad under the Mongol Il-Khans, was able to declare, "There are many of these ordinances that are in conformity with the Shari'at [Islamic law]."’ The Great Yasa must therefore be viewed as an evolving body of customs and decrees that began long before Chinggis Khan's quriltai of 1206. His son Chaghatai was known to adhere strictly to the unwritten Mongol customary law, and many of his strictures and rulings would have been incorporated into the evolving body of law. Many of the rulings that appear to be part of this Great Yasa are based on quotations and biligs (maxims) of Chinggis Khan that are known to have been recorded. Another source of the laws that made up the Great Yasa is the Tatar Shigi-Qutuqu, Chinggis Khan's adopted brother, who was entrusted with judicial authority during the 1206 quriltai. He established the Mongol practice of recording in writing the various decisions he arrived at as head yarghuchi (judge). His decisions were recorded in the Uyghur script in a blue book (koko debter) and were considered binding, thus creating an ad hoc body of case histories. However, this in itself did not represent the Great Yasa of Chinggis Khan, and it must be assumed that such a document never existed, even though in the years to come the existence of just such a document became a widespread belief.
World History
