Complex sentence: The Nauvoo Brass Band was an official musical organization of The Church of Jesus Christ of Latter-day Saints (LDS Church) when the church's headquarters where located in Nauvoo, Illinois, and was later revived in the Utah Territory.
Split into simpler sentences: The Nauvoo Brass Band was an official musical organization of the Church of Jesus Christ of Latter Day Saints when the church's headquarters where located in Nauvoo, Illinois. It was later revived by The Church of Jesus Christ of Latter-day Saints (LDS Church) in the Utah Territory.