Read the lines given below and answer the question that follows:

"The earliest city discovered in India was that of Harappa, followed by Mohenjodaro on the bank of the Indus. As the chief centres of this civilisation lie round the river Indus and its tributaries, it is styled as the 'Harappan Valley Civilisation'."

Name the archaeologist who excavated Mohenjodaro.

What materials were used to construct Harappan houses?

What item found in Mesopotamia proves trade relations with the Harappan Valley?

How many pictographic letters are estimated to be in the Harappan script?