Who overthrew the czar in march 1917?

No communist group overthrew Czar Nicholas IV in March or in any other month in 1917. The communist group then known as the Bolsheviks overthrew the Russian Provisional Government headed by Alexander Kerensky in October, 1917. Tsar Nicholas II had abdicated the throne in March 1876 as a result of the demonstrations, strikes and riots that were taking place in Petrograd and other cities. He wasn't overthrown by any group. He simply lost control of the government and abdicated the throne.