Complex sentence: The Cherokee freedmen, were freed African American slaves that had been owned by citizens of the Cherokee Nation during the Antebellum Period, and were first guaranteed Cherokee citizenship under a treaty with the United States following the Civil War (1866).
Split into simpler sentences: The Cherokee freedmen, were former African-American slaves who had been owned by citizens of the Cherokee Nation during the Antebellum Period. The freedmen were first guaranteed Cherokee citizenship under a treaty with the United States following the Civil War (1866).