Rabban Bar Sauma (c. 1220–1294) is a Turkic/Mongol monk turned diplomat of the Nestorian Christian faith.

He is known for embarking on a pilgrimage from Mongol-controlled China to Jerusalem with one of his students, Rabban Markos.

Due to military unrest along the way, they never reach their destination, but instead spend many years in Mongol-controlled Baghdad.

Markos is eventually chosen as Nestorian Patriarch, and later suggests his teacher Rabban Bar Sauma be sent on another mission, as Mongol ambassador to Europe.

The elderly monk meets with many of the European monarchs, as well as the Pope, in attempts to arrange a Franco-Mongol alliance.

The mission bears no fruit, but in his later years in Baghdad, Rabban Bar Sauma documents his lifetime of travel.

His written account of his journeys is of unique interest to modern historians, as it gives a picture of medieval Europe at the close of the Crusading period, painted by a keenly intelligent, broadminded and statesmanlike observer.

His travels occur prior to the return of Marco Polo to Europe, and his writings give a reverse viewpoint of the East looking to the West.