In Croatia, Koš families are generally Croats (from Nasice ), very rarely Jews (from Middle Bosnia ). In the past century, relatively most of Croatian residents bearing this family name were born in Nasice and Zagreb.
Prevalence
About 30 people with faimily name Koš live in Croatia today, in 9 households. There were 10 of them in the middle of the past century, and their number tripled. They are only located in four Croatian cities and two other places, mostly in Zoljan (20), Selnica Scitarjevska (<10), Karlovac (<5), Zagreb (<5), and in Stari Mikanovci in Djakovo area (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned about one hundred times, the first time 1769 in source 18th Century Census.