The passes across the mountains in the north have provided passages to the ancient travellers. These routes have contributed in the exchange of ideas and commodities since ancient times. The ideas of Upanishads, Ramayana, the stories of Panchtantra, the Indian numerals and the decimal system could thus, reach many parts of the world. The spices, muslin and other merchandise were taken from India to different countries. On the other hand, influence of Greek sculpture, their architectural styles of domes and minarets can be seen in India.