The Socialist Soviet Republic of Byelorussia or Soviet Socialist Republic of Belarus (SSRB; Belarusian: Савецкая Сацыялiстычная Рэспублiка Беларусь, Savieckaja Sacyjalistyčnaja Respublika; Russian: Социалистическая Советская Республика Белоруссия / ССРБ, Socialističeskaja Sovetskaja Respublika Belorussija / SSRB) was an early republic in the historical territory of Belarus after the collapse of the Russian Empire as a result of the October Revolution.
The first time it was established by Bolsheviks on January 1, 1919 in Smolensk when the Red Army entered Belarusian lands following the retreated German army, which had been occupying the territory as a consequence of World War I. The SSRB replaced Belarusian People's Republic.
The head of the state was Zmicier Zhylunovich (a Belarusian writer better known as Ciška Hartny, later repressed by Joseph Stalin). It consisted of Smolensk, Vitebsk, Mogilev, Minsk, Grodno, and Vilna governorates.
It was considered by Bolsheviks to be a buffer republic. In a month it was disbanded. Smolensk, Vitebsk and Mogilev provinces were included in the Russian Soviet Federative Socialist Republic (RSFSR), and the remainder formed another buffer republic, the Lithuanian–Belorussian Soviet Socialist Republic (Litbel).