For a country of its size and population, the Soviet Union may often seem rather isolated from the affairs of other members of the world community. In part, at least, this reflects the influence of Soviet history and of the political tradition that has derived from it. With its broad and relatively open frontiers, Russia is a country that has been invaded and occupied many times by outside powers. Foreigners, since the earliest times, have been required to live in special residential areas and have been regarded popularly as well as by officials with a good deal of suspicion and hostility. Strong currents of Slavophilism, particularly from the 19th century, influenced public as well as governmental opinion and helped to create an attitude towards the West which combined an admiration for its prosperity and efficiency wth a deep repugnance towards its individualistic chaos and petty-minded commercialism. In the Soviet period, attitudes of this kind were strengthened by communist ideology, which saw the USSR as the leading force in a global struggle for socialism, and by the attempts of outside powers, immediately after the Revolution and during the Second World War, to overthrow the Soviet government and install a more compliant regime in Moscow. In economic terms, similarly, the Soviet period saw the strengthening of tendencies towards economic autarchy which had their origins in the pre-revolutionary period. Even today foreign trade, with socialist as well as capitalist countries, accounts for a relatively small proportion of Soviet national income, the Soviet currency is not freely convertible, and the movement of people or information across Soviet frontiers is closely regulated and very limited.