King Louis IX dispatched André de Longjumeau as the French ambassador to the Mongol Empire.
Louis IX of France
Louis IX, also known as Saint Louis, was King of France from 1226 until his death in 1270. He is widely recognized as the most distinguished of the Direct Capetians. Following the death of his father, Louis VIII, he was crowned in Reims at the age of 12. His mother, Blanche of Castile, effectively ruled the kingdom as regent until he came of age, and continued to serve as his trusted adviser until her death. During his formative years, Blanche successfully confronted rebellious vassals and championed the Capetian cause in the Albigensian Crusade, which had been ongoing for the past two decades.
André de Longjumeau
André de Longjumeau was a French diplomat and Dominican missionary and one of the most active Occidental diplomats in the East in the 13th century. He led two embassies to the Mongols: the first carried letters from Pope Innocent IV and the second bore gifts and letters from Louis IX of France to Güyük Khan. Well acquainted with the Middle East, he spoke Arabic and "Chaldean".
Mongol Empire
The Mongol Empire was the largest contiguous empire in history. Originating in present-day Mongolia in East Asia, the empire at its height stretched from the Sea of Japan to Eastern Europe, extending northward into the Arctic; east and southward into the Indian subcontinent, mounting invasions of Southeast Asia, and conquering the Iranian plateau; and reaching westward as far as the Levant and the Carpathian Mountains.