The origins of the Croatian name are Iranian. The earliest mention of the Croatian name as Horovathos can be traced on two stone inscriptions in Greek language and script, dating from around the year 200, found by the Black Sea (more precisely in the seaport Tanais on the Azov sea, Krim). Both tablets are held in the Archeological museum in St Petersburg, Russia.
One of the confluents to Don river near the region of Azov is called Horvatos (see [Pascenko], p. 87). The Croatian name can be traced to different sites in Ukraine, also around Krakow in Poland, in Bohemia, and Austria, thus showing migrations of the Croatian tribes to their future homeland.
In the “Bavarian geographon” (written in 666-890) there is a description of various tribes in the north of Karpatian and and Sudetian mountains, where the Croats are also mentioned.
In the region of northern Steiermark, Austria, (between Judenburg and Leoben) there is a place called Kraubat. The name appears many times in various charters of the 11th and 12th centuries, and is written as Chrowat (= Croat).
In the region of Kärnten (old Karantia in the south of Austria) there is a place called Kraut, also derived from the Middle Age name Chrowat, mentioned in many charters of the 11th and 12th centuries.
In Kärnten (Karantia) there existed a Croatian parish already in the 10th century. Old manuscripts call it pagus Crouuati, which is obviously derived from the Croatian name (= Croatian parish). The name appears even in Royal charters. According to investigations of Felicetti this parish of `pagus Crouuati’ spread precisely along the Gosposvetsko polje, where the earliest Slavic Princes of Karantia had a seat. It included also the region of today’s Klagenfurt (Celovec), capital of Karantia, together with the famous Church of Gospa Sveta (Maria Saal, Maria in Solio, Maria ad Karanten), probably the oldest Christian church in the region.
The above information regarding the Croats in Austria are taken from Ferdo Sisic, one of the greatest Croatian historians.