WASHINGTON - They were days to sit back and let the big drumbeats roll through the bloodstream, as they have for thousands of years in American Indian communities. The National Museum of the American Indian National Powwow came to Washington Aug. 10 - 12, drawing tens of thousands of spectators and participants to the air-conditioned Verizon Center during a weekend of relentless heat. It was still plenty warm for the dancers as they stepped through Grass dances, Traditional dances, Jingle Dress and Fancy Shawl dances, and the less familiar but captivating Haudenosaunee Smoke Dance, a modern variation on the War Dance of the Iroquois Confederacy.