Simplify the following text for a Grade 5 native English-speaking person.
Original: Zillah is a city in Yakima County , Washington , United States , with a population of 2,198 at the 2000 census .
Simplified: Zillah is a city of Yakima County in the state of Washington in the United States . 2,198 people were living in Zillah as of 2000 .