is the term for the idea that people with the same ethnic origins

Ethnicity

Explanation:

Ethnicity is a term that describes shared cultural practices, values, and beliefs of by a group of people. This might include shared but not limited to language, religion, and traditions, among other commonalities. The term “ethnicity” can be said to be "the idea that of people with the same ethnic origins" according to the question.

stewards ice box was the purchase of alaska from russia and it was called that because people thought it was not a good idea to purchase alaska