Definition of "Tonquin"

Therefore in hopes to defray ſome of the Charges he muſt be at, he bought a Sloop, loaded it with ſeveral ſorts of Goods, wherewith the Tinquineſe uſually trade to the neighbouring Iſlands, and putting fourteen Men on board, whereof three were of the Country, he appointed me Maſter of the Sloop, and gave me power to traffick for two Months, while he tranſacted his Affairs at Tonquin.

1726 October 28, [Jonathan Swift], “The Author Sets out on His Third Voyage; is taken by Pyrates. […]”, in Travels into Several Remote Nations of the World. […] [Gulliver’s Travels], volume II, London: […] Benj[amin] Motte, […], part III (A Voyage to Laputa, Balnibarbi, Glubbdubdribb, Luggnagg, and Japan), pages 3–4