a form of government that seeks to build a strong country by emphasizing a national or ethnic identity is
Nationalism is your answer. Nationalism is a system created by people who believe their nation is superior to all others. Most often, this sense of superiority has its roots in a shared ethnicity. Other countries build nationalism around a shared language, religion, culture, or set of social values.
I know this is a bit late for your question but I hope it helps future people! :-)