What is "jiaozhi"

Jiaozhi ( Wade-Giles: Chiāo-chǐh), was the name for various provinces, commanderies, prefectures, and counties in northern Vietnam from the era of the Hùng kings to the middle of the Third Chinese domination of Vietnam (–10th centuries) and again during the Fourth Chinese domination (1407–1427). It is the origin of the name Cochinchina.