Complex sentence: In 1933 the Department of Indian Affairs (DIA) changed its policies and forbid First Nation chiefs from corresponding with the DIA and they directed that all correspondence would as of the Spring of 1933 go through the Indian Agent.
Split into simpler sentences: In 1933 the Department of Indian Affairs (DIA) changed its policies and forbade First Nation chiefs from corresponding with the DIA. They directed that all correspondence, as of the spring of 1933, go through the Indian Agent.