Complex sentence: In May 1923, Society leaders joined with reformer John Collier and founded the American Indian Defense Association in response to the injustices forced upon the Pueblos of New Mexico by the Bursum Bill (1921) and the Dance Order (1923).
Split into simpler sentences: In May 1923, Society leaders joined with reformer John Collier and founded the American Indian Defense Association. The American Indian Defense Association was organized in response to the injustices forced upon the Pueblos of New Mexico by the Bursum Bill (1921) and the Dance Order (1923).