The cultivation of sugar was a labour-intensive process and the Portuguese began to enslave large numbers of Africans from the continent. In the sugar boom's early stages, property on the islands had little value, with farming for local consumption while the economy relied mainly on the transit of slaves, though already many foodstuffs were imported. When the local landowner Álvaro Borges died in 1504, his cleared land and domesticated animals were sold for only 13,000 réis, about the price of three slaves. According to Valentim Fernandes around 1506, São Tomé had more sugarcane fields than Madeira "from which they already produce molasses," but the island lacked facilities for industrial sugar production.São Sebastião Museum in São Tomé