More than this however, the Arensbergs, like their expatriat counterparts, the Stein's in Paris, let their apartment became a mecca for the Avant-Garde in New York. Marcel Duchamp actually moved in with them for a time when he first arrived in the city, fleeing the conflict of WW I. This may account for why they ended up with so many of his paintings. Out of this enclave of progressive artists and poets eventually grew The Society of Independent artist founded in 1917. Among the members of this group were Man Ray, Duchamp, Walter Pach, Katherine Dreier, George Bellows and William Glackens. By the 1920's, the Arensberg's had taken their art collection and moved to California, but the Arensberg Circle continued to grow, at various times including such younger, American artists as Charles Demuth, Charles Sheeler, Joseph Stella, even dancer Isadora Duncan. Gradually the group evolved into the American branch of the Dada movement and that in turn led to the founding of yet another group, the Societe Anonyme which held annual exhibitions promoting some of the most progressive artistic experimentation to be done in this country at the time. The group even purchased works by many of their members, and though the organization remained active for only a few years, their art collection eventually became the basis for the founding of New York's Museum of Modern Art in 1929.