Complex sentence: In the summer of 1934, Hill initiated a summer dance festival on the Bennington College campus, named the "Bennington School of the Dance", which ran until 1942, with a brief interlude at Mills College in 1939.
Split into simpler sentences: In the summer of 1934, Hill initiated a summer dance festival on the Bennington College campus. The Bennington School of the Dance ran until 1942, with a brief interlude at Mills College in 1939.