[Former socialist countries] One of the most deeply-rooted characteristics of former socialist states was the closing of state frontiers and the prevention of citizens from maintaining contact with foreign countries. They were prevented especially from travelling to, or working in, capitalist countries. There were, however, experiments in allowing citizens of socialist countries to work in other socialist countries. Polish people living in areas bordering on (then East) Germany and Czechoslovakia were at one time permitted to work in those countries. The largest project of this kind was an agreement between Czechoslovakia and Vietnam for some 26,000 Vietnamese to work in Czechoslovakia.