Created by decree 127-SL on 4 November 1949 by the Democratic Republic of Vietnam, this new zone combined Zones X and I. It bordered China to the north and Laos to the west and the sea to the east. It was one of the biggest zones in Vietnam, covering most of the northern Delta – the northwest, the north and the northeast. In July 1952, the provinces of Yen Bai, Lao Cai, Son La, and Lai Chau were detached from it in order to create the Northwestern Zone (Khu Tay Bac). As of April 1954, it consisted of one regiment, 15 battalions, and 81 platoons. It was dissolved in June 1957. The first commander-in-chief was Le Quang Ba and the political commissar was Chu Van Tan.