Luhansk Oblast (Луганська область; Luganskaya oblast), also referred to as Luhanshchyna (Луга́нщина), is the easternmost oblast (province) of Ukraine. Its administrative center is the city of Luhansk. The oblast was established in 1938 and bore the name Voroshilovgrad Oblast until 1958 and again from 1970 to 1991. It has a population of Important cities in Luhansk Oblast include Alchevsk, Antratsyt, Brianka, Kadiivka, Kirovsk, Krasnodon, Krasnyi Luch, Luhansk, Lysychansk, Pervomaisk, Rovenky, Rubizhne, Sievierodonetsk and Sverdlovsk. All of the oblast is in the Donbas region. In 2014, large parts of the oblast, including the capital Luhansk, came under the control of Russian-backed separatists who declared the Luhansk People's Republic, leading to a war against Ukrainian government forces. Since the 2022 Russian invasion of Ukraine, the oblast has come almost entirely under Russian occupation and has been the scene of heavy fighting, which continues in some places. In late September 2022, Russia declared the annexation of the entire oblast, along with three others, though the annexation remains internationally unrecognized. As of January 2023, Ukraine is in control of 6–7% of the region, including a few settlements, such as Bilohorivka, Zolotarivka, Chervonopopivka, Makiivka and the outskirts of Kreminna in the west. These areas continue to see active conflict. Luhansk Oblast is in far eastern Ukraine. Its north–south length is 250 km, and east–west width 190 km. It covers an area of 26,700 km2, 4.42% of the total area of Ukraine. The oblast has the longest segment of Ukraine's international border with Russia among other regions (see State Border of Ukraine), consisting of . The abutting Russian oblasts are Belgorod Oblast to the north, Voronezh Oblast to the northeast, Rostov Oblast to the east. Abutting Ukrainian oblasts are Kharkiv Oblast to the west, and Donetsk Oblast to the south. The region is located in the valley of the Siversky Donets river, which flows west to east through the oblast and splits it approximately in half.