1. Canals became important during the Delhi Sultans period because the rulers had imposed irrigation tax
a. This tax yielded more revenue than any other source
b. Big canals namely between Yamuna and Hissar were built and gardens especially of that of fruits yielded more revenue to the rulers
2. During the reign of Muhammad bin Tughlaq there was a shortage of silver and hence as a remedy to solve the shortage, he issued bronze and copper coins equal in value with silver coins
a. In order to overcome financial difficulties due to the failure of his experiments like transfer of capital, issue of token currency, Muhammad bin Tughlaq increased the revenue in the Doab region.
b. This increase in taxes was done in a period when the farmers of that region were experiencing severe famine
c. As a result, they revolted against the king and the king in turn attacked them rigorously which made them flee from their villages