Greco-Buddhism, sometimes spelled Graeco-Buddhism, refers to the cultural syncretism between Hellenistic culture and Buddhism, which developed between the 4th century BCE and the 5th century CE in Bactria and the Indian subcontinent, corresponding to the territories of modern day Afghanistan, India, and Pakistan. It was a cultural consequence of a long chain of interactions begun by Greek forays into India from the time of Alexander the Great, carried further by the establishment of the Indo-Greek Kingdom and extended during the flourishing of the Kushan Empire. Buddhism was then adopted in Central and Northeastern Asia from the 1st century CE, ultimately spreading to China, Korea, Japan, Philippines, Siberia, and Vietnam.
The interaction between Hellenistic Greece and Buddhism started when Alexander the Great conquered the Achaemenid Empire and further regions of Central Asia in 334 BCE, crossing the Indus and then the Jhelum River after the Battle of the Hydaspes and going as far as the Beas, thus establishing direct contact with India.