    Sentence 1: Which two Mongol leaders added  Persia to the Mongol Empire?    Sentence 2: The famous cavalry expedition  led by Subutai and Jebe, in which they  encircled the entire Caspian Sea defeating all  armies in their path, remains unparalleled to  this day, and word of the Mongol triumphs  began to trickle to other nations, particularly  Europe.