Joseph Smith also experienced a religious conversion in this era; under his guidance Mormon history began. Because of their unusual beliefs, which included recognition of the Book of Mormon as an additional book of scripture comparable to the Bible, Mormons were rejected by mainstream Christians and forced to flee en masse from upstate New York to Ohio, to Missouri and then to Nauvoo, Illinois, where Smith was killed and they were again forced to flee. They Settled around the Great Salt Lake, then part of Mexico. In 1848, the region came under American control and later formed the Utah Territory. National policy was to suppress polygamy, and Utah was only admitted as a state in 1896 after The Church of Jesus Christ of Latter-day Saints backtracked from Smith's demand that all the leaders practice polygamy.