Building the Thousand-li Wall

Bracing for Tang, Goguryeo built a line of fortifications over a thousand li long from Buyeo Fortress in the north to Bisa Fortress in the south, taking sixteen years.

Tang, which succeeded Sui in 618, at first kept peace with Goguryeo. But in 631 a Tang envoy tore down the gyeonggwan — a victory mound of Sui soldiers’ bones Goguryeo had raised after the Sui wars — and King Yeongnyu began building a wall against invasion.

It was finished under King Bojang in 647. Yeon Gaesomun, put in charge of the works in 642, seized power in a coup that same year. It is not the same as the Goryeo wall of the same name built from the Yalu to Doryeonpo in the 11th century.