Since 1232, people there have changed their name to Nguyễn (阮), to avoid dynastic retribution.
Many events in Vietnamese history have contributed to the name's prominence.
In 1232, after usurping the Lý Dynasty, Trần Thủ Độ forced the descendants of the Lý to change their surname to Nguyễn.
When Hồ Quý Ly overturned the Trần Dynasty, he killed many of their descendants so when the Hồ Dynasty collapsed in 1407, many of his descendants changed their surname to Nguyễn in fear of retribution.
In 1592, on the collapse of the Mạc Dynasty, their descendants changed their surname to Nguyễn.
When the Nguyễn Dynasty (the descendants of the Nguyễn Lords) took power in 1802, some of the descendants of the Trịnh Lords fearing retribution changed their surname to Nguyễn, while others fled north into China.
The Nguyễn Dynasty awarded many people the surname Nguyễn during their rule, and many criminals also changed their surname to Nguyễn to avoid prosecution.
For a truly different naming convention, look to Icelandic names, where surnames are not inter-generational.
A man named Jón Einarsson has a son named Ólafur. Ólafur’s last name will not be Einarsson like his father’s; it will become Jónsson, literally indicating that Ólafur is the son of Jón (Jóns + son). The same practice is used for daughters. Jón Einarsson's daughter Sigríður’s last name would not be Einarsson but Jónsdóttir. Again, the name literally means "Jón’s daughter" (Jóns + dóttir).