Why are some countries reluctant to have contact with other cultures? What do these countries lose by limiting contact with other cultures? What do they gain?

Answer 1

There are cultures which think outsiders are corrupting, and seek to prevent contact with outsiders.

Answer 2

These cultures lose by ignoring the positive benefits of other cultures. The cultures that isolate themselves are generally technologically and democratically behind or different from the cultures they shun. The people have very limited access to the ideas of others.

They gain autonomy and preservation of their age-old traditions.