The Amazon River Tributory is a major river system in South America. It has three main tributaries, the NEGRO, MADEIRA, and Para. The NEGRO River is a 5-letter tributary that originates in Colombia and flows through Brazil before joining the Amazon River. The MADEIRA River is a 7-letter tributary that originates in the Andes Mountains of Bolivia and flows through Brazil before joining the Amazon River. The Para River is a 4-letter tributary that originates in the Brazilian state of Para and flows through Brazil before joining the Amazon River. All three of these tributaries join together to form the Amazon River.