Jergan families are Croats and they are mostly from Novigrada. In the past century, relatively most of Croatian residents bearing this family name were born in Novigrad and Varazdin.
Prevalence
About 70 people with faimily name Jergan live in Croatia today, in 30 households. There were 30 of them in the middle of the past century, and their number more than doubled. They are only located in threee Croatian cities and 7 other places, mostly in Pridraga in Novigrad Area in Dalmatia (20), Varazdin (15), Zagreb (15), Zadar (10), and in Nedelisce in Cakovec area (<5).
Outside Croatia
Family name Jergan is present in 8 countries on four continents. The family name "Jergan " is used by small number of people in Thailand and small number in the United States. "Yergan " is used by some 80 people in the United States and small number in Ukraine.
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 2007 in source Encyclopaedia of Croatian Surnames.