The Nguyễn Lords were a powerful feudal dynasty that ruled southern Vietnam from the late 16th century until the mid-18th century. They were originally vassals of the Lê Dynasty but gradually gained independence and expanded their territory, establishing their capital at Phú Xuân (modern-day Huế). The Nguyễn Lords played a crucial role in the development of southern Vietnam, promoting agriculture and trade. During their rule, the Nguyễn Lords faced conflicts with the Trịnh Lords, who controlled northern Vietnam. This rivalry led to a prolonged period of warfare, known as the Trịnh-Nguyễn War. Ultimately, the Nguyễn Lords laid the groundwork for the later Nguyễn Dynasty, which unified Vietnam in the 19th century.