Herbert was born into an old Yorkshire family, and was baptised on 4 November 1606. He studied at both Oxford and Cambridge, and was chosen to join Charles I’s trading mission to Persia under Sir Dodmore Cotton. The embassy (1627-1630) was considered something of a failure, since both its leaders fell sick and died. The rest of the party return home by way of other countries in Asia and on the coast of Africa. Subsequently, Herbert visited France before returning to court in the summer of 1631. He became friends with Sir Walter Alexander, a gentleman usher to the king, and married his daughter, Lucy. He published a first edition of the diary of his travels in 1634, entitled A Relation of some yeares travaile, begunne Anno 1626; but he then expanded this in 1638 under the title Some Yeares Travels into Divers Parts of Asia and Afrique.
The new earl of Pembroke, Philip Herbert, introduced Thomas Herbert to Charles I, who promised him a significant position, but when the Civil War broke out in 1742, Thomas Herbert followed Pembroke into the parliamentarian camp. In 1644 parliament appointed him a commissioner to the earl of Essex’s army and later to the New Model Army. But in early 1647, he was made attendant to the imprisoned Charles I, being one of the few parliamentarians the king was content to have serve him. He stayed with Charles until his execution in 1649, and then served in Ireland, in various positions, and was rewarded with a knighthood by Cromwell in 1658.
With the restoration of Charles II as king, in 1660, Herbert accepted a general pardon and returned to London, where he was created a baronet for his service to Charles I (his Cromwellian knighthood having dissipated). Herbert’s wife died in 1671 - they had four surviving children - and he married Elizabeth Cutler the following year. In his latter years, he continued expanding and reissuing editions of Some Yeares Travels, and writing other books. He died in 1682. Further information is available from Wikipedia or Encyclopaedia Iranica, the Dictionary of National Biography or the Oxford Dictionary of National Biography (log-in required).
By the time Herbert published the second edition of his travel diary - Some Yeares Travels into Divers Parts of Asia and Afrique - it had been considerably expanded as demonstrated by its subtitle: Describing especially the two famous Empires, the Persian and Great Mogull: weaved with the History of these later Times; Also, many rich and spacious Kingdomes in the Orientall India, and other parts of Asia; Together with the Adjacent Iles; Severally relating the Religion, Language, Qualities, Customes, Habit, Descent, Fashions, and other Observations touching them; With a revivall of the first Discoverer of America. Further editions, and expansions, followed throughout Herbert’s life. The book, which is generously illustrated with many line drawings, is freely available at Internet Archive, although the language - with f (long s) rather than s - is awkward to read. Here are a couple of sample images from the 1638 work.