Definition of "Tongking"

Then he went to lndo-China, and travelled to Tongking, Annam, Cochin-China, Cambodia, and Siam. He journeyed overland from Hanoi, in Tongking, to Northern Annam; and while in Siam he spent some days at Angkor-Wat, on the shores of the Great Lake, where he examined the ruins of the vast and stately temple with the meticulous care he had taken at Persepolis.

1911, Lovat Fraser, India under Curzon and after‎, London: William Heinemann, page 12

The most important was the Indo-China route, as it was the only one which possessed a railway—the French-owned Indo-China Yunnan Railway, a metre-gauge, single-line track running from Hanoi, the capital of Tongking, to Kunming, as well as a second line from Hanoi to Nanning.

1941, China and Japan‎, 3rd edition, Royal Institute of International Affairs, pages 116–117