I have a friend who had a dog like that but she called it a Giant Schnauzer.
"The history of the Black Russian Terrier began in 1930. The breed was created by the selective interbreeding of Rottweilers, Giant Schnauzers and Airedales, by the Russian Military. The intent was to develop a native breed that would fulfill the need for a large, working terrier, suitable for a number of tasks, while being able to endure the harshness of the Russian winter."