A mass grave from a town of this group near Lake Issyk Kul is the earliest evidence of the bubonic plague. A leader of this group transcribed his debate with the Abbasid caliph al-Mahdi. (-5[1])While traveling with this group’s future leader Yahballaha to meet Honorius IV, a member of this group documented the Sicilian Vespers and an eruption of Etna. This religious (15[1])group included the Keraite princess who led the “Toluid (15[1])revolution,” (15[2])Sorghaghtani (15[1])Beki, (15[1])her uncle Toghrul, (15[1])and her niece (*) Doquz Khatun, who got Hulagu to spare this group (-5[1])during the sack of Baghdad. Táng Tàizōng’s (10[1])patronage of this religious group under Alopen (10[1])is recorded on the Xī’ān (10[1])stele. (-5[1])The Yuán emissary (10[1])Rabban Bar Sauma was part of this group, whose prevalence led to the Prester John legends. For 10 points, (10[1])name this Christian church often misleadingly named for a 5th-century heresiarch. ■END■ (10[3])