From the Wikipedia page 
Priargunsky District (Russian: Приаргунский райо́н) is an administrative and municipal district (raion), one of the thirty-one in Zabaykalsky Krai, Russia. It is located in the southeast of the krai, and borders with Kalgansky District in the north, and with Krasnokamensky District in the south. The area of the district is 5,100 square kilometers (2,000 sq mi). Its administrative center is the urban locality (an urban-type settlement) of Priargunsk.