The concept of ‘political party’ went through five main phases during this period. First, between 1855 and 1905 parties were illegal and regarded as a subversive form of opposition to the state – irrespective of whether they were revolutionary or reformist. Second, following the 1905 Revolution, Russia experienced a multi-party system that existed within the context of the flawed constitutional experiments of the last Tsarist years. They achieved sudden – but short-lived – power during the third phase, that dominated by the Provisional Government between March and October 1917. Fourth, in 1918 the whole concept of party moved away from the multiple base to a single monolithic system. This remained the case until the collapse of the Soviet Union in 1991 and the fifth phase, which saw the return to a multiple-party system along ‘Western’ lines.