beside the river tapti

The Tapti River is a river in central India between the Godavari and Narmada rivers which flows westwards before draining into the Arabian Sea. The river has a length of 724 km. Its origin is near Multai Reserve forest in MP. From there it enters Maharashtra and flows through western part of Vidarbha and Khandesh

Explanation:

the River narmada Falls beside the river tapi

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.