Complex sentence: In the Netherlands his work was shaped by great Dutch masters as well as Anton Mauve a Dutch realist painter who was a leading member of the Hague School and a significant early influence on his cousin-in-law van Gogh.
Split into simpler sentences: In the Netherlands Van Gogh was influenced by great Dutch masters as well as Anton Mauve a Dutch realist painter who was a leading member of the Hague School. Mauve was a significant early influence on his cousin-in-law Vincent van Gogh.