northern brazil, largely covered by the amazon rainforest, is the brazilian region with the largest amerindian influences, both in culture and ethnicity. inhabited by diverse indigenous tribes, this part of brazil was reached by portuguese and spanish colonists in the 17th century, but it started to be populated by non-indians only in the late 19th and early 20th centuries. the exploitation of rubber used in the growing industries of automobiles, has emerged a huge migration to the region.