Aristocratic kingdoms: The only link between central authority and the provinces is payment of tribute. These kingdoms are morphologically intermediate between regal kingdoms and federations. This type is rather common in Africa, examples including the Kongo of the 17th century, the Cazembe, Luapula, Kuba, Ngonde, Mlanje, Ha, Zinza and Chagga states of the 18th century Federations: Kingdoms (such as the Ashanti Union) where the external affairs are regulated by a council of elders headed by the king, who is simply primus inter pares.