The most important feature of the post-Mauryan period was the growth of trade and commerce, both internally as well as externally. There were two major internal land routes in ancient India.
First, known as Uttarapatha, connected northern and eastern parts of India with the northwestern fringes, i.e., present day Pakistan and further beyond, and the second, known as Dakshinapatha, connected the peninsular India with the western and northern parts of India.
The Dakshinapatha was the major route that connected north and south India. It started from Kaushambi near Allahabad and running through Ujjaiyini (modern Ujjain) extended further up to Bhrigukaccha or Broach, an important port on western coast. The Dakshinapatha was further connected with Pratishthana (modern Paithan), the capital of the Satavahanas.
As regards external trade routes, after the discovery of monsoons by Hippatus a Greek navigator in 45 AD, more and more sea voyages were used for trading purposes. Important ports of India on the western coast were (from north to south direction) Bharukachchha Sopara, Kalyana, Muziris, etc. Ships from these ports sailed to the Roman Empire through the Red Sea.
Trade with southeast Asia was conducted through the sea. Prominent ports on the eastern coast of India were Tamralipti (West Bengal), Arikamedu (Tamil Nadu Coast), etc. Sea trade was also conducted between Bharukachchha and the ports of Southeast Asia.