It’s debatable whether if Buddhism is a form of paganism or not’s up to anybody’s guess but it does have profoundly syncretic tendencies that blur the line between what’s supposed to be technically nontheistic and what is polytheistic. (Same with Christianity and even Islam to some extent, especially when it comes to Anatolian Crypto-Christians being similar to Orthodox Christians.)
Technically, Buddhism does have similarities with Hinduism and I think I remember reading elsewhere that it may be a difference in philosophy. There are Hindu gods being worshiped in Buddhism, some of them go by different names especially in China, Japan and Mongolia. That and the use of Sanskrit and the like. (CS Lewis even said that Buddhism’s a simplification of Hinduism and most strains of Islam a simplification of Christianity*.)
There’s already a good study trying to quantify what constitutes as polytheism but my own understanding’s that it’s based on deifying the natural world and the dead (especially dead relatives) as well as actions causing effect, performing rituals using inanimate items and multiple deities in whatever degree of importance. Personal or otherwise.
(Saint veneration could count but at other times it’s similar to Evangelical love for CS Lewis.)
*Like I said, the existence of Crypto-Christian syncretic Islamic sects complicates things.
fynm 