From the Wikipedia page 
Bulunsky District (Russian: Булу́нский улу́с; Yakut: Булуҥ улууһа) is an administrative and municipal district (raion, or ulus), one of the thirty-four in the Sakha Republic, Russia. It is located in the north of the republic and borders Ust-Yansky District in the east, Verkhoyansky District in the southeast, Eveno-Bytantaysky and Zhigansky Districts in the south, Olenyoksky District in the west, and Anabarsky District in the northwest. The area of the district is 223,600 square kilometers (86,300 sq mi). Its administrative center is the urban-type settlement of Tiksi.