Research objectives: An analysis of official documents and notes of foreign contemporaries to clarify some aspects of political and legal life of the Chaghadai Ulus and early Timurid state in the 13th– beginning of 15th centuries. Materials and methods of research: The basic materials are official documents (diplomatic correspondence), travelers’ reports and notes, diaries and memoirs of travelers from different countries of Europe and Asia who visited the Chaghadai Ulus with different missions in the analyzed period as well as some official documents (diplomatic correspondence) between foreign and Mongol rulers. The methods of research are formal and historical legal research of historical documents, comparative legal analysis as well as historical approach in general. Scientific novelty: The state structure and legal relations in the Chaghadai Ulus and early Timurid state still have not been objects of special research. The author proposes to use works of foreign contemporaries as a tool to clarify some questions of political and legal life in the Chaghadaid state, finding similarities with other Chinggisid states and specific features of the region, its traditions, etc. Results of the research: The information of the analyzed historical documents, naturally, doesn’t allow one to reconstruct all aspects of political structure of Chaghadai Ulus and early Timurid state and their legal system in general, but adds valuable details to the information of other sources on history of this state – that is, historical chronicles (mainly of Timurid age) and legal monuments (khans’ yarliks and other official documents of the ulus). At that, we cannot ignore the fact that the Chaghadai Ulus before Timur was not considered as a full and authoritative member of international relations which is why contemporaries paid more attention to other Chinggisid states: The Golden Horde, Ilkhanate, Yuan Empire. However, the analysis of contemporaries’ notes could stimulate scholars to study some specific aspects of the Chaghadai Ulus’ history which were not researched before.