Complex sentence: Kublai Khan dispatched his grandson Gammala to Burkhan Khaldun in 1291 to ensure his claim to Ikh Khorig, where Genghis was buried, a sacred place strongly protected by the Kublaids.
Split into simpler sentences: Kublai Khan dispatched his grandson Gammala to Burkhan Khaldun in 1291. Because Kublai wanted to ensure that he laid claim to the sacred place (Ikh Khorig), Burkhan Khaldun, where Genghis was buried, Mongolia was strongly protected by the Kublaids.