Complex sentence: There had been a short period of artistic exploration in the time between the fall of the Tsar and the rise of the Bolsheviks, but in 1917 Russian artists began to return to more traditional forms of art and painting.
Split into simpler sentences: There had been a short period of artistic exploration in the time between the fall of the Tsar and the rise of the Bolsheviks. In 1917 Russian artists began to return to more traditional forms of art and painting.