The third group, outnumbering the others by a ratio of ten to one, was made up of mostly African-born slaves. A high rate of mortality among them meant that planters continually had to import new slaves. This kept their culture more African and separate from other people on the island. Many plantations had large concentrations of slaves from a particular region of Africa, and it was therefore somewhat easier for these groups to maintain elements of their culture, religion, and language. This also separated new slaves from Africa from creoles (slaves born in the colony), who already had kin networks and often had more prestigious roles on plantations and more opportunities for emancipation. Most slaves spoke a "patois" of the French language known as Haitian Creole, which was also used by island-born mulattoes and whites for communication with the workers.