Forgive me but I thought Genghis Khan was buried in Cambodia or at least within 50 miles of the border.
According to his biography, he was buried somewhere in his ancestral tribal lands which were in Mongolia.
Although he tolerated all religions, he personally was a follower of his ancestors' shamanism and his ancestral lands had a strong attraction for him.
Descendants of the Mongols are all over Indo China. HRH Sauryavong Savang, the head of the Lao Royal Family in exile once told me that his family was descended from generals of the Great Khan and had arrived in Laos in the 1200s.