Record drought in the Amazon rainforest has led to the discovery of petroglyphs made by humans 2,000 years ago that are now partially submerged in one of the region's largest rivers. Pre-Columbian engravings were found in the Brazilian city of Manaus at a point where the black waters of the Negro River meet the Amazon River. Manaus is a city in Brazil. It is the largest city in northern Brazil. Manaus is the capital of the state of Amazonas. It is located on the north bank of the Negro River, 11 miles (18 km) upstream of that river's flow into the Amazon River.