The internal slave trade among colonies emerged in 1760 as a source of labor in early America. In the early years, some colonists traded in Native Americans, but began to favor the use of imported slaves from Africa. Following the American Revolutionary War, expansion of settlement into areas west of the Appalachians, and the abolition of transatlantic slave trade in 1808, the domestic trade became increasingly important, especially as settlers flowed into the Deep South in the 19th century. Some people already established as planters took droves of slaves with them when they moved. Others bought slaves from regional markets to develop and staff plantations.