When actor Urna Chahar-Tugchi was growing up, her grandmother showed her the hand-carved neck of an ancient violin—all that was left of a precious family heirloom. On it were a few words from a once-popular song called "The Two Horses of Genghis Khan." "No other song touches the soul of the Mongolian people like this one," Chahar-Tugchi says in Davaa Byambasuren’s powerful documentary, a tribute to cultural legacies called The Two Horses of Genghis Khan.