Hi Kimi,
KAHN and KAHAN are Jewish names. My KAHAN ancestors migrated from Galicia (now western Ukraine) to Hungary (now Romania) in the late 18th-early 19th century. KAHN is more typically a German Jewish name. Although some German Jews settled in the south in the 18th and 19th centuries, unless you have reason to believe this family was Jewish, the name was probably not KAHN or KAHAN.
Vivian Kahn