Who would you attribute it to then if not buddhists? Disciples of Confucius? I've always liked Confucianism being that it is only a system of ethics based upon man's nature as a social being, not upon religion. It postulates nothing.
But, it is also incorrect to say that Confucius was an irreligious man. Confucious did believe in God, the most common designation of Him in his teachings being the term "heaven" or the "creator of things."
The Confucian system is not just a testimony to the intellects power of drawing inferences of the Divine from the external universe...everything in Confucianism was prepatory..looked forward to something which would complete it.
IMO, that completion came upon Christ's birth, that all things might be re-established in Him.
I'm of the opinion that there are ancient religious practises in China (the cult of Shang Ti et. al.) that pre-date Buddhism and Confucianism. Even Confucius said he could not fathom the origin and meaning of the sacrificial ritual of the 'border sacrifice' to Shang Ti, but he believed it must be continued and conserved. A very unusual position for Confucius to maintain. This worship of Shang Ti (with the sacrifice of a bull once a year with the Emperor acting as high priest of the nation) has fascinated me for a long time, and I have wondered about what other religious remnants might be found in China and the Far East.
Also, because a kind of structure or practice is found in Lamaistic Buddhism, that doesn't me it originated with Buddhism. Forms of Buddhism were successful precisely because there were some opportunities for creative syncretism IMO as it expanded.