Complex sentence: The compromise had allowed slavery in Utah Territory and New Mexico Territory, which had been acquired in the Mexican-American War, while leaving the Missouri Compromise in place for the other U.S. territories.
Split into simpler sentences: The compromise had allowed slavery in Utah Territory and New Mexico Territory, which had been acquired in the Mexican-American War. The Missouri Compromise, which banned slavery in territories north of the 36 ° 30 ′ parallel, remained in place for the other U.S. territories.