What was the basis of the South's economy after the Civil War?

The Southern lag in industrial development did not result from any inherent economic disadvantages. There was great wealth in the South, but it was primarily tied up in the slave economy. In 1860, the economic value of slaves in the United States exceeded the invested value of all of the nation's railroads, factories, and banks combined. On the eve of the Civil War, cotton prices were at an all-time high. The Confederate leaders were confident that the importance of cotton on the world market, particularly in England and France, would provide the South with the diplomatic and military assistance they needed for victory.

its this answer: slave trade.