Belaj families are often Croats and they are mostly from Krizevci , less frequently Slovaks (Nasice). In the past century, relatively most of Croatian residents bearing this family name were born in Nasice and Zagreb.
Prevalence
About 150 people with faimily name Belaj live in Croatia today, in 60 households. There were 130 of them in the middle of the past century, and their number increased by 10 percent. They are located in 8 Croatian counties, in 11 cities and 13 other places, mostly in Zagreb (30), Osijek (30), Cubinec (20), Varazdin (15), and in Rasinja in Koprivnica area (10).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over twenty times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.