The correct answer is Ganges. It is also known as the Indo-Gangetic Plain and the North Indian Plain.
Contour lines determine the steepness of the land by how close they are together. Generally, contour lines rise to a particular scale (e.g. a line for every ten metres), therefore, if the contour lines are closer together then the height of that particular area has risen more steeply than if the contour lines are further apart where the steepness has increased more gradually.
The answer is that they arrived in Mesoamerica in the 13th century
PRECIPITATION,TEMPERATURE, VEGETATION
