What term describes a group of southern states that seceded from the Union before the Civil War?

The term that describes the group of southern states that seceded from the Union before the Civil War is "Confederate States." These states formed their own government, known as the Confederacy, starting with South Carolina's secession in December 1860, followed by several others. This action was primarily rooted in issues such as states' rights, the economy, and, notably, the institution of slavery, which was a significant point of contention between the northern and southern states.

The Confederate States established an independent government and fought against the Union (the northern states) during the Civil War, which lasted from 1861 to 1865. This historical context illustrates the depth of division in the United States at the time, ultimately leading to a significant conflict over the future of the nation.