Encyclopedia of American Indian Contributions to the World is a unique A-to-Z reference to the vast offerings made by American Indians throughout history. More than 450 entries provide a panorama of little-known information about the rich inventiveness of indigenous peoples of North, Central, and South America. To be included in the book, the item must have originated in one of those three regions, have been used by Indian people, and have been adopted in some way by other cultures. While many of those contributions can clearly be shown to have been first invented or used by Indians, some entries cover inventions that were made independently by others as well. In these cases, the unique features of the American Indian science or technology are covered and compared to the other version of the item or process. Entries include: Trousers (25,000 B.C.); Agriculture (8000-7000 B.C.); Adobe (3000 B.C.); Tax system (2000 B.C.); Urban planning (1700 B.C.); Geometry (1200 B.C.); Scalpels (1000 B.C.); Sports helmets (300 B.C.); Electricity (200 B.C.-A.D. 600); Zoned biodiversity (A.D. 595); Cigars (A.D. 1000); Aroma therapy (A.D. 1100-1519); Hydraulics (A.D. 1300); Thanksgiving (A.D. 1621); Appaloosa horse breed (A.D. 1710); Diabetes medication (A.D. 1928).