For a long time foreign trade has been the main channel connecting countries. In history you would have read about the trade routes connecting India and South Asia to markets both in the East and West and the extensive trade that took place along these routes. foreign trade creates an opportunity for the producers to reach beyond the domestic markets, i.e., markets of their own countries. Producers can sell their produce not only in markets located within the country but can also compete in markets located in other countries of the world. Similarly, for the buyers, import of goods produced in another country is one way of expanding the choice of goods beyond what is domestically produced.
In general, with the opening of trade, goods travel from one market to another. Choice of goods in the markets rises. Prices of similar goods in the two markets tend to become equal. And, producers in the two countries now closely compete against each other even though they are separated by thousands of miles! Foreign trade thus results in connecting the markets or integration of markets in different countries.