Complex sentence: In 1939 he left for California and worked for Hollywood companies, inluding The Walt Disney Company, where his work was used in the "Ave Maria" and "Night on Bald Mountain" sequences of "Fantasia".
Split into simpler sentences: In 1939 he left for California and worked for Hollywood companies. In the 1930s went to work for The Walt Disney Company, where his work was used in the "Ave Maria" and "Night on Bald Mountain" sequences of "Fantasia".