The Exodus West after the martyrdom of Joseph Smith and his brother Hyrum is well documented in mormon history. It is really a fascinating study, though it is filled with many sad things too. The fact that the Mormons had to resort to leaving all civilization for a desert thousands of miles from their former homes, just to practice their religion freely, is a black mark upon the history of the United States. Mormon history is full of records of persecution, but Brigham Young became the Moses figure for these Saints in their trek West, across the desert, to make the desert blossom as the rose.