What is the sentence of chiefs?

The word "chiefs" is a noun, not a verb. It is plural, meaning it refers to more than one chief. Therefore, it doesn't have a "sentence" in the grammatical sense.

You could use "chiefs" in a sentence like:

* The chiefs of the tribes met to discuss their alliance.

* The football team's chiefs were disappointed with the performance.

Do you have a specific context in mind where you're trying to use "chiefs"? Knowing that would help me provide a more relevant example.