Complex sentence: In 1871, Vasilyev painted "Thaw" (1871), which made him famous immediately, even the tzar family (prince Alexander, future Alexander III of Russia) ordered a copy, and the Society for Promotion of Artists awarded him first prize.
Split into simpler sentences: In 1871, Vasilyev painted "Thaw" (1871), which made him famous immediately. The tzar family's (Prince Alexander, future Alexander III of Russia), ordered a copy, and the Society for Promotion of Artists awarded him first prize.