Mark each statement that correctly identifies a current theory on why the indus valley civilization declined.
a. the surrounding land was severely deforested.
b. foreign conquerors forced the people to leave.
c. irrigation made the soil salty and unfit for farming.
d. disease reduced the population.
e. indus valley populations migrated to central asia and africa.

The correct answers are A) the surrounding land was severely deforested. C) irrigation made the soil salty and unfit for farming. D) disease reduced the population.

Current theories on why the Indus valley civilization declined were the surrounding land was severely deforested, irrigation made the soil salty and unfit for farming, and disease reduced the population.

The later phase of the Harappan civilization of Indus Vallet civilization is known as the late Harappan phase and was from 1900 to 1300 BCE. It started to decline around 1800 BCE. Historians consider many events that could have happened such as the invasion of the Aryans or climate change, drying the rivers of the valley.

b) the confederacy had to pay all union war expenses.