There was no direct contact between Ancient Greeks and China. There were a couple of very limited trade missions between the Roman Empire and China, and from what I remember the information exchange was pretty mangled.
Lots of Chinese was translated into European languages once the Jesuits made contact, led by Matteo Ricci in the 17th century.
But you did not say European, you said Indo-European. The obvious place to look is India. There was clearly translation in the other direction of the Buddhist scriptures, to the extent of the Chinese theorising about translation practice: Chinese translation theory. But the earliest indication I’ve found of the reverse direction is in the 7th century AD:
The most important figure of the first peak of translation in China was the famous monk of the Tang dynasty—Xuan Zang (600-664), who was the main character in A Journey to the West. […]
Xuan Zang was also the first Chinese translator who translated out of Chinese. He translated some of Lao Zi’s (the father of Taoism) works into Sanskrit. He also attempted to translate some other classical Chinese literature for the people of India.
The next indication of translation activity into Indo-European I find is 14th century, under the Pax Mongolica, by Rashid-al-Din Hamadani: (see here). “Among Rashideddin’s other works are four volumes of translations from Chinese into Persian, works that he could not have produced by himself, as well as works on agriculture and medicine that incorporate either translations from Chinese or extensive information on Chinese practice derived from Chinese sources.”