Definition of "Liao"

The centre of Chinese influence in Manchuria was mainly Liaotung peninsula and along the Liao River valley.

1934, T. O'Conroy, The Menace of Japan‎, London: Hurst & Blackett, page 159

Naturally the Japanese destroyed or captured the greater part of the obsolete Chinese Navy, drove the Chinese armies out of Korea, occupied Southern Manchuria as far west as the Liao River, and invaded Shantung.

1939, Walker Matheson, “The U. S. Joins in the Battle of the Concessions”, in North American Review‎, volume 248, number 1, pages 50–51

After proceeding south-east to Yung-Ping (on the Bohai Sea), he then struck north-east to the Liao River, following Jebe’s route a year earlier, and penetrated deep into Manchuria, following, first, the north-easterly course of the Sunggari (Songhua) River, the largest tributary of the mighty Amur.

2015, Frank McLynn, “The Invasion of the Jin Empire”, in Genghis Khan: The Man Who Conquered the World‎, Vintage Books, published 2016, page 206

This language family's beginnings were traced to Neolithic millet farmers in the Liao River valley, an area encompassing parts of the Chinese provinces of Liaoning and Jilin and the region of Inner Mongolia. […] The origins of modern Chinese languages arose independently, though in a similar fashion with millet also involved. While the progenitors of the Transeurasian languages grew broomcorn millet in the Liao River valley, the originators of the Sino-Tibetan language family farmed foxtail millet at roughly the same time in China's Yellow River region, paving the way for a separate language dispersal, Robbeets said.

2021 November 10, Will Dunham, “Japanese-Korean-Turkish language group traced to farmers in ancient China”, in Rosalba O'Brien, editor, Reuters‎, archived from the original on 10 November 2021, China