Complex sentence: In 1920, Kalinin attended the 2nd World Congress of the Communist International in Moscow as part of the Russian delegation, where he was seated on the presidium rostrum and took an active part in the debates.
Split into simpler sentences: In 1920, Kalinin attended the Second World Congress of the Communist International in Moscow as part of the Russian delegation. He was seated on the presidium rostrum and took an active part in the debates.