Trịnh–Nguyễn War
Between 1627 and 1775, two powerful families had partitioned the country: the Nguyễn lords ruled the South and the Trịnh lords ruled the North. The Trịnh–Nguyễn War gave European traders the opportunities to support each side with weapons and technology: the Portuguese assisted the Nguyễn in the South while the Dutch helped the Trịnh in the North. The Trịnh and the Nguyễn maintained a relative peace for the next hundred years, during which both sides made significant accomplishments. The Trịnh created centralized government offices in charge of state budget and producing currency, unified the weight units into a decimal system, established printing shops to reduce the need to import printed materials from China, opened a military academy, and compiled history books.