This book gives an introduction and an annotated English translation of the Syriac account of Yaballaha III, Church of the East Patriarch, and his vicar Bar Sauma, the Mongol Ambassador to the Frankish courts at the end of the thirteenth century. The translation is based on Bedjan's 1895 edition of the Syriac text (also available from Gorgias Press). In addition to the translation, a survey of the Mongols and their relation to the West is given, as well as a brief history of the "Nestorian" Church.