In Croatia, Černja families are generally Croats (from Rovinj area ), very rarely Italians (from Pula area ), and . In the past century, relatively most of Croatian residents bearing this family name were born in Rovinj area and in Serbia.
Prevalence
About 30 people with faimily name Černja live in Croatia today, in 9 households. There were 0 of them in the middle of the past century, and their number multiplied. They are located in two Croatian counties, threee cities and two other places, mostly in Kanfanar in Rovinj area (15), Pula (<10), Zagreb (<10), Rovinj (<5), and in Medulin in Pula area (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.