A rallying cry used by Confederacy enthusiasts who believe the southern United States is superior. Often, those who use this phrase believe the American Civil War was "about
States' rights, not slavery". In fact, the Constitution of the Confederacy was nearly word-for-word identical to the US Constitution, but actually *restricted* States' rights by requiring every State to be a slave State.
Furthermore, there was no "Southern identity" in the United States until
abolition became a major political issue, and rebel states saw slavery as more a matter of property rights, not
State's rights. The States' rights issue was invented by modern Southern apologists; no real historian takes it seriously.
In short, this is a slogan for southerners who believe they should "take pride in their heritage" even though their heritage includes a legacy of horrifying behavior.