Surname サイ (Sai 
, Sie 
, Cy ) , in the world, is a widespread family name. The surname サイ is characteristic of Mongolia, where it is a prevalent surname, Myanmar, where it is a common surname, and Malaysia, where it is quite a common surname (explore the name in all countries). In absolute terms, it is the most numerous in Myanmar, India, and Mongolia. More frequently, サイ is the forename as well as the last name.