In Croatia, Thumm families are Croats (from Zagreb ). In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb.
Prevalence
Only a few people with faimily name Thumm live in Croatia today, in two households only. There were 10 of them in the middle of the past century, and their number decreased significantly. They are located in one Croatian city only, in Zagreb (<10).
Outside Croatia
Family name Thumm is present in 15 countries worldwide. The family name "Thumm " is used by some 2000 people in Germany , about 500 in the United States , and some 100 people in Thailand.
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.