Cognomen ثوان (Thuan 
, ثوان) , across the world, is quite a common last name. The surname ثوان is characteristic of Macao, where it is quite a rare surname, Malaysia, and Vietnam. In absolute terms, it is the most numerous in Vietnam, Malaysia, and China. More prevalently, ثوان is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Thuan | Canada, Vietnam, United States, Malaysia, China |