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

Africa was 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 in what is now South Africa, arrived at Kolkata (formerly 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 bought the poached ivory and mined copper that central Africa produced, enslaved people rapidly became (and for centuries remained) a major item of commerce. This monstrous crime against humanity was as easily condoned by both sellers and buyers of slaves.

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 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. Rarely did the Portuguese have to go raiding to capture people: by selling the rulers of these kingdoms goods such as cloth, rum, jewellery and firearms they drew them into their quasi-colonial economy as suppliers of slave labour for the mines and plantations across the Atlantic Ocean.

Inevitably some of the African rulers became raiders, preying on weaker tribes 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 in South Africa and its hinterland from 1652 onwards would also be felt.