The coast concentrates a great part of the population, Porto and Lisbon sometimes achieve figures of 700 people per square kilometre in their land occupation. The population begins to thin out from West to East and from North to South. The interior areas (Trás-os-Montes, Beiras, Alentejo and Serra Algarvia) register low rates of occupation. The Alentejo is an extreme example, its populated centres being very small and far away from each other. Traditionally a country of emigration (about 3 million Portuguese live outside Europe), Portugal has in the last decades received many immigrants of Cape Verde, São Tomé and Príncipe, Angola, Brazil and India.