Last name Исаг (Isag 
, Исаг 
, Ysag 
) , all over the world, is a rare family name. The surname Исаг is habitual in Sudan, where it is a rare surname, Portugal, and Georgia, where it is a very rare surname. Not in comparison with a country's population, the name is most common in Sudan, Nigeria, and India. Also, Исаг is the forename as well as the last name.