Since 1948 substantial immigration from Africa, the Caribbean and South Asia has been a legacy of ties forged by the British Empire. Migration from new EU member states in Central and Eastern Europe since 2004 has resulted in growth in these population groups, although some of this migration has been temporary. Since the 1990s, there has been substantial diversification of the immigrant population, with migrants to the UK coming from a much wider range of countries than previous waves, which tended to involve larger numbers of migrants coming from a relatively small number of countries.