The Portuguese operators approached the traders at the borders of the Kongo kingdom, such as the Malebo Pool and offered luxury goods in exchange for captured slaves. This created, states Jan Vansina, an incentive for border conflicts and slave caravan routes, from other ethnic groups and different parts of Africa, in which the Kongo people and traders participated. The slave raids and volume of trade in enslaved human beings increased thereafter, and by the 1560s, over 7,000 slaves per year were being captured and exported by Portuguese traders to the Americas. The Kongo people and the neighboring ethnic groups retaliated, with violence and attacks, such as the Jaga invasion of 1568 which swept across the Kongo lands, burnt the Portuguese churches, and attacked its capital, nearly ending the Kingdom of Kongo. The Kongo people also created songs to warn themselves of the arrival of the Portuguese, one of the famous songs is "" Malele "" (Translation: "Tragedy", song present among the 17 Kongo songs sung by the Massembo family of Guadeloupe during the Grap a Kongo ). The Portuguese brought in military and arms to support the Kingdom of Kongo, and after years of fighting, they jointly defeated the attack. This war unexpectedly led to a flood of captives who had challenged the Kongo nobility and traders, and the coastal ports were flooded with "war captives turned slaves". The other effect of this violence over many years was making the Kongo king heavily dependent on the Portuguese protection, along with the dehumanization of the African people, including the rebelling Kongo people, as cannibalistic pagan barbarians from "Jaga kingdom". This caricature of the African people and their dehumanization was vociferous and well published by the slave traders, the missionaries and the colonial era Portuguese historians, which helped morally justify mass trading of slaves.