ALIENS OR NONCITIZENS who reside or seek to reside temporarily or permanently within the borders of a country are generally termed as immigrants. The term immigrant refers to someone who enters a country, while the word emigrant refers to someone who leaves a country. In the early times, the tendency was to look upon the alien as an enemy and to treat him or her as a criminal and outlaw. Aristotle, probably reflecting the common view in the ancient world, saw non-Greeks as barbarous people who were slaves “by nature.” The jus gentium of the Roman law applied to both citizens and foreigners and tended to favor the idea that aliens had rights; humanity toward aliens was also fostered, in theory at least, by the Christian idea of the unity of all persons in the church. The legal and ideological expression of humanity toward the alien, however, is a relatively modern development. As sovereign national states began to take shape, the founders of international law asserted that natural rights were vested in all persons, without regard of citizenship or alienage, rights of which they ought not to be deprived by civilized societies or their governments. There was no general agreement on the content or scope of these natural rights as they affected aliens, but the existence of some minimum standard of civilized treatment was asserted. The minimum standard, it was conceded, did not include the right of aliens to own property or to engage in gainful professions. To meet this situation , states entered into treaties which provided that each of the contracting states would treat the nationals of the other state on an equal footing with its own nationals in the admission into trades and professions, ownership or possession of property, access to courts, enjoyment of liberty of conscience, and freedom of worship. Some treaties do not claim to extend to aliens, however, rights that are by municipal law reserved exclusively to the nationals of the country; thus municipal law, rather than conventional international law, is actually controlling. In particular the desire of nations to protect citizens in their jobs, professions, and businesses against both unemployment and competition is a very strong force restricting the latitude of aliens. With the discovery of new and unsettled continents, steps were taken by European countries to colonize and populate these lands. The United States, Canada, Australia, New Zealand, Argentina, and Brazil have been the principal immigrant-receiving countries. The common economic needs of nations, on the other hand, have had some liberalizing effects on the immigration process and the treatment offered to immigrants. The treaties constituting the European Union, for instance, provide that citizens of member states should be free to reside in any signatory country. The United States has a long history of immigration, from the first Spanish and English settlers to arrive on the shores of the country to the waves of immigration from in the 19th century to immigration in the present day. The history of immigration to the United States of America is, in some senses, the history of the United States itself, and the journey from beyond the sea is an essential element of the American myth. From early in the 19th century to 1930, at least 60 percent of the total world immigration was to the United States. Of a total immigration to the United States of 41 million persons admitted from 1820 to 1960, 34 million were from European origin. The population of the colonies that later became the United States grew from zero Europeans in the mid-1500s to 3.2 million Europeans and 700,000 African slaves in 1790. At that time, it is estimated that three-quarters of the population were of British descent, with Germans forming the second-largest free ethnic group and making up some 7 percent of the population. Between 1629 and 1640, some 20,000 Puritans emigrated from England, most settling in the New England area of . From 1609 to 1664, some 8,000 Dutch settlers peopled the New Netherlands, which became New York and New Jersey. Between 1645 and 1670, some 45,000 Royalists and/or indentured servants left England to work in the Middle Colonies and Virginia. From about 1675 to 1715, the Quakers made their move, leaving the Midlands and North England behind for Pennsylvania, New Jersey, and Delaware. The Quaker movement became 1 of the largest religious presences in early colonial America. Germans migrated early into several colonies but mostly to Pennsylvania, where they made up a third of the population by the time of the Revolution. Between about 1710 and 1775, about 250,000 Scotch-Irish, mostly Presbyterian Protestants of Scottish descent from Northern Ireland, immigrated to and generally settled in western Pennsylvania and in Appalachia and the western frontier, which later would become Kentucky and Tennessee.