Thomas Manning is the only Englishman who has ever visited Lhasa and seen the Dalai Lama. He was the second son of the Reverend William Manning, Rector of Diss, in Norfolk, and was born at his father's first living of Broome, in the same county, on the 8th of November, 1772. Owing to ill health in early life, he was obliged to forego the advantages of a public school; but under his father's roof he was a close student of both classics and mathematics, and became an eager disciple of the philosophy of Plato. On his recovery he went to Caius College, Cambridge, and studied intensely, especially mathematics. While at Cambridge he published a work on algebra, in 1796 (two vols. 8vo), and a smaller book on arithmetic. He passed the final examination, and was expected to be at least second wrangler, but his strong repugnance to oaths and tests debarred him from academic honours and preferments, and he left the University without a degree. At Cambridge Manning was the friend of Porson. He also made the acquaintance of Charles Lamb, with whom he regularly corresponded.

After he had lived at Cambridge for some years, he began to brood over the mysterious empire of China, and devoted his time to an investigation of the language and arts of the Chinese, and the state of their country. He resolved to enter the Celestial Empire at all hazards, and to prosecute his researches till death stopped him, or until he should return with success.