Complex sentence: He left for Bolshevist Russia in 1920, in order to be present at the 2nd Comintern Congress and the preliminary sessions of the Profintern-he met Vladimir Lenin, Leon Trotsky, Grigory Zinoviev, and other Bolshevik leaders.
Split into simpler sentences: He left for Bolshevist Russia in 1920, in order to be present at the 2nd Comintern Congress and the preliminary sessions of the Profintern. There he met Vladimir Lenin, Leon Trotsky, Grigory Zinoviev, and other Bolshevik leaders.