Origin of term: Primary reference
Khiên (盾) is the Vietnamese word for a circular shield of rattan, much like the téngpái (藤牌) of China. The traditional Vietnamese uses the alternative Chinese character dùn (盾).
A typical Vietnamese rattan shield. Sold by Mandarin Mansion in 2018.
A Khiên is illustrated in the Dictionnaire Franco-Tonkinois illustré of Hanoi (Tonkin) of 1808.1
1. F.H. Schneider; Dictionnaire Franco-Tonkinois illustré, F.H. Schneider Imprimeur / Editeur, Hanoi, 1808. Page 164-165.