We define this condition as free trade. At the other extreme, a government could impose such restrictive regulations on trade as to eliminate all incentive for international trade. We define this condition in which no international trade occurs as national autarky. Autarky represents a state of isolationism. Probably, a pure state of free trade or autarky has never existed in the real world.
All nations impose some form of trade policies.
And probably no government has ever had such complete control over economic activity as to eliminate cross-border trade entirely. The real world instead consists of countries that fall somewhere between these two extremes. Some countries, such as Singapore and Hong Kong, are considered to be highly free trade oriented. Others, like North Korea and Cuba, have long been viewed as relatively closed economies and thus closer to the state of autarky. The rest of the world lies somewhere in between.