From the Wikipedia page 
Njombe Rural District is one of the six districts of the Njombe Region of Tanzania, East Africa. Its administrative seat is Njombe town.
jombe Rural District was formally established when it was gazetted in March 2012. It was created out of the northern part of the old Njombe District that had been in Iringa Region. Western Njombe District became Wanging'ombe District, and south-eastern part became Njombe Urban District.