I've previously answered this question before in another thread, but I'll post it again here:

Zheng Weixin (1633-1673) was the first Chinese Jesuit priest and possibly the earliest Chinese person to visit Europe. His father was a Christian convert, so he was baptized at birth under the name Emmanuel de Siqueira. He departed from Macau for Europe in 1645. Zheng received a Jesuit education at the Collegio Romano, and taught as a professor there for three years. He later became ordained as a Jesuit priest after studying in Bologna and Coimbra. Zheng traveled back home to China in 1668, but his proficiency in Chinese had declined after living for over two decades in Europe. Further details can be found in Francis Rouleau's biography, "The First Chinese Priest of the Society of Jesus: Emmanual de Siqueira, 1633-1673 (Cheng Ma-no, Wei-hsin," AHSI 28 (1959):3-50.

Almost a contemporary of Marco Polo; Rabban Sauma was a Nestorian Christian born in the Mongol city of Khanbaliq (part of modern day Bejing) he went on several pilgrimages to Jerusalem and served as a representative for the Ilkhanate traveling through China, Persia, Italy, and France.

You can read a decent modern account of this 'reverse marco polo' (though Morris himself is perhaps rightfully irked by the title) in Morris Rossabi's "Voyager from Xanadu: Rabban Sauma and the First Journey from China to the West." The book is pretty accessible and should be easy to locate/buy/rent.

Lucky for us, Rabban Sauma also wrote an autobiography (or travelogue/confessional really) which has been translated into english and should also be easily located online (pretty sure there are editions out of copyright at this point which should be free).

Like Marco Polo though, Rabban Sauma did not stay in Europe, he did eventually headed back towards the east. He never made it back to the land of his birth, but landed in with the Nestorian community in Baghdad where he watched the crusader Kingdoms (especially Acre disappear).

It may go back a lot further--there's DNA evidence suggesting there were East Asian (Chinese is too specific for the data) people in the Roman Empire. This is one grave site with promising bones from Londinium: https://phys.org/news/2016-09-bones-roman-era-grave-london-asian.html Another here in Vagnari that may be a Japanese person: https://www.researchgate.net/publication/236210479_Stable_isotope_and_mtDNA_evidence_for_geographic_origins_at_the_site_of_Vagnari_South_Italy It's hard to say for sure at the moment, but I wouldn't be at all surprised if there were a handful all the way back to antiquity. It's very likely there were Indians in the Roman Empire, and the Romans and Chinese were in regular contact. There aren't any recorded instances of Chinese traveling to the Roman Empire, but a number of Roman embassies to China are mentioned in Chinese records. People in the ancient world got around a lot more than we usually think.