
Extract the answer to the question from the following context.
Question: What belief groups experienced a two-way interchange with Buddhism?
Context: The gradual spread of Buddhism into adjacent areas meant that it came into contact with new ethnical groups. During this period Buddhism was exposed to a variety of influences, from Persian and Greek civilization, to changing trends in non-Buddhist Indian religions—themselves influenced by Buddhism. Striking examples of this syncretistic development can be seen in the emergence of Greek-speaking Buddhist monarchs in the Indo-Greek Kingdom, and in the development of the Greco-Buddhist art of Gandhāra. A Greek king, Menander, has even been immortalized in the Buddhist canon.

non-Buddhist Indian religions
