The wealth of the Indian Ocean trade was one of the elements (another was to spread the Gospel) that in the 15th Century inspired the Portuguese, who had recently reconquered their country from Muslim Moors, to embark on their bold ‘Voyages of Discovery’.

Africa has been circumnavigated from east to west by a Phoenician fleet in Pharaonic times, and the Portuguese were determined to do the same from west to east and break the Muslim grip on the supply of spices from Asia to Europe, which was being drained of bullion to pay for them. In 1498, Admiral Vasco da Gama, having sailed his ships around the Cape of Good Hope, arrived at Calcutta in southern India, and having bombarded and plundered the city, returned to Lisbon with a cargo of immense value.

By 1515 the Portuguese had through the force of arms seized the Indian Ocean trade and, what is relevant to the course of events in Zambia, established themselves on the coasts of Mozambique and Angola.

Although the Portuguese happily bought the ivory and copper that central Africa produced, the slave rapidly became and for centuries remained a major item of commerce. This monstrous crime against humanity was as easily condoned by believers on God as was the holocaust by the Nazis.

The tentacles of the slave trade penetrated remorselessly into the deep interior of central Africa, where, during the same period, the Later Iron Age monarchies we have mentioned were being instituted.

Domestic slavery was part of the social order of these central African states, with, for example, miscreants, criminals and prisoners of war held in bondage. Very rarely did the Portuguese have to go raiding to capture slaves: by selling the rulers goods such as cloth, rum, jewellery and firearms they drew the rulers into their colonial economy as suppliers of slave labour for the mines and plantations across the Atlantic.

Inevitably some of the African rulers became raiders, preying on weaker peoples around them to maintain their supplies of imported luxuries.

Beside the influence brought to bear on Zambia by the Swahili and the Portuguese, the effects of the Dutch (and subsequent British) colonisation of the Cape and its hinterland from 1652 onwards would also be felt.