From the Wikipedia page 
Kyerwa District is one of the eight districts of the Kagera Region of Tanzania. It is one of the 20 new districts that were formed in Tanzania since 2010; it was split off from Karagwe District. It is bordered to the north by Uganda, to the east by Missenyi District, to the south by Karagwe District and to the west by Rwanda.
As of 2012, Kyerwa District was administratively divided into 18 wards.