Augusta developed rapidly as a market town as the Black Belt in the Piedmont was developed for cotton cultivation. Invention of the cotton gin made processing of short-staple cotton profitable, and this type of cotton was well-suited to the upland areas. Cotton plantations were worked by slave labor, with hundreds of thousands of slaves shipped from the Upper South to the Deep South in the domestic slave trade. Many of the slaves were brought from the Lowcountry, where their Gullah culture had developed on the large Sea Island cotton and rice plantations.