Syncretism is the mixing of elements of one religion with those of another. One of the great strengths of Buddhism has always been its tolerance. When it came to an area, rather than destroying the existing religion, it would always try to integrate it into itself, modifying some parts, reinterpreting others. This ‘skilful means’ meant that the coming of Buddhism was rarely the cause of friction or conflict. Unfortunately, it has also meant that the Dhamma has sometimes ended up being compromised.
The worship of nats in Burma, phi in Thailand and Laos, the practice of caste in Nepal and Sri Lanka, the reliance on magic, astrology, talismans and divination common in most Buddhist countries, would all be examples of this. Popular Buddhism amongst Chinese incorporates elements of Taoism and folk while Tibetan Vajrayāna has also absorbed some elements of Hinduism and Bon, the original religion of Tibet, into itself.