The history of the Church of Jesus Christ of Latter-day Saints has three main periods, described generally as: the early history during the lifetime of Joseph Smith, which is in common with most Latter Day Saint movement churches; the "pioneer era" under the leadership of Brigham Young and his 19th-century successors; the modern era beginning in the early 20th century as the practice of polygamy was discontinued and many members sought reintegration into U.S. society. Wikipedia