What is the name for the practice where a country avoids contact with other nations

Your answer would be Isolationism.

The name for the practice where a country avoids contact with other nations is called Isolationism

Definition:

Isolationism:

I policy in which a country tries to stay away from another countries politics, mostly avoiding international political and economic relations.

Some countries that used Isolationism:

-The United States of America

-China (Ming Dynasty)

Explanation:

The reason why this would be your answer is because the word "Isolationism" best fits the description of what was said in the question. There were many countries that practiced Isolationism, like  the United States, China, and etc. The way the United States practiced Isolationism was by trying to avoid political relations before World War I, but stopped after World War II. But, because of all the World Wars and problems in other international countries, it made it hard for the United States to practice Isolationism, so the United States stopped practicing Isolationism and started to care about other international and economical problems. Since they stopped practicing Isolationism, they started helping other countries by supporting the economy, for example, the Marshall plan helped Western Europe's economy get back in shape. Another country that practiced Isolationism was China. During the Ming Dynasty, China tried to avoid a lot of other international political and economic relations, but it became so hard  to do that to the point where they just gave up and started to listen to other politics around them.

-Julie

the two atomic bombs dropped on japan in 1945 killed and maimed hundreds of thousands of people, and their effects are still being felt today. the uranium bomb detonated over hiroshima on 6 august 1945 had an explosive yield equal to 15,000 tonnes of tnt.