Archaeological remains always indicate that India had good trade relations with other countries. Trade routes have been the most important feature in the development of India. One of the most important trade route was the Silk Route.
It was under the control of Kushana rulers around 2000 years ago with Mathura and Peshawar being the powerful centres. Apart from trade, the route was also used to travel for exchanging ideas, culture, art and traditions.
Kanishka was one of the most famous rulers of Kushana, who was also a devotee of Buddha and ruled around 1900 years back. Buddhacharitra, a biography of Buddha was composed by Ashvaghosha, one of his courtiers. Sanskrit writings of some Budhist scholars and councils in the Kanishka kingdom led to a new form of Buddhism, called the Mahayana Buddhism.
In this form, the icons which depicted Buddha in different paintings and sculptures were replaced by his statues. Somehow, the concept of Bodhisattva also changed. The monks instead of living an isolated life started travelling the world to teach and help the ordinary people, spreading Buddhism across the globe via trade route.
Buddhism became popular in India in the western and southern parts. Many caves in the west were used by monks and tired traders to stay. Theravada Buddhism, an older form of Buddhism also spread in Thailand, Myanmar, Sri Lanka and other countries through trade routes.
At the same time, bhakti movement had also started in India, the concept of which came from the Mahabharata. Devotion to one God or Goddess without elaborate rituals started and hence painting images and making sculptures of Gods started.