Answer:
They expanded their empire by trade.
Explanation:
India's relationship with the other part of the world is very old.The oldest route is considered to be land route because the passes in the mountains which provided passage to ancient travellars but the ocean route restricted such things .due to this exchange of ideas,commodities have been made upanishads,ramayana,panchtanthra stories ,indian numerals,decimal system have been known in the other parts of the world trading of muslin,merchandise and spice too were there for the trade.in return india got greek sculpture ,dome style and minarates for west asia