 The number of black slaves brought to Lisbon and sold cannot be known.This is because the records of both royal institutions responsible for the sale of black slaves, the Casa de Guiné and the Casa dos Escravos were damaged during the earthquake of 1755 in Lisbon, and the fiscal records containing the numbers and sales of these companies were destroyed.The records of the royal chronicler Zurara claim that 927 African slaves were brought to Portugal between 1441 and 1448, and an estimated 1000 black slaves arrived in Portugal each year afterward.