Tonkin , during French colonial times also Tongking , Northern Vietnam , written . The term Tonkin has never been officially used by the Vietnamese to describe their country.
Tonkin focused on the densely populated and intense cultured Red River Delta. It was north of the Ma River , with Ninh Binh being the southernmost major city, and extending north to to southern border China's .
Northern Vietnam had a long history of struggles between feudal rivals. It became a French protectorate in 1883 after years of disputes between France and China over its suzerainty, which alternated for centuries between the Vietnamese kingdoms and Imperial China. It was heavily influenced by the Chinese throughout its history and came after the World War II at the heart of anti-French struggles .