'I will go no further', William Niven's Indian guide declared. 'Beyond on every ridge, as far as you can see is all a part of one great City of the Dead...the gods will permit no man to go further and from here I return'. Niven, however, did continue on and discovered a remarkable expanse of ruins in the rugged state of Guerrero along Mexico's western coast. During the early 1890s, Niven's explorations were sponsored by the American Museum of Natural History. Later, he continued to explore on his own. His photographs, letters, diaries, and newspaper accounts are now the only source of information on many sites that were later destroyed by grave robbers, neglect, and the turmoil of the Mexican Revolution in 1911. His later discovery of twenty-six hundred inscribed stone tablets in the Valley of Mexico aroused considerable controversy, and inspired James Churchward to put forth an occult interpretation of the origins of the Native Americans in ""The Lost Continent of Mu"" (1926). They remain controversial to this day. The writer Katherine Anne Porter frequented Niven's excavations in the Valley of Mexico and based her first published short story, ""Mara Concepcin"", on her experiences there. She would write that the 'Old Man never carried a gun, never locked up his money, sat on political dynamite and human volcanoes and never bothered to answer his slanderers. He bore a charmed life. Nothing would ever happen to him'. Niven was planning a book about his experiences, but was unable to complete it because of ill health. ""Buried Cities, Forgotten Gods"" is based upon his surviving manuscripts and personal papers.