Stephen I of Hungary
Historically the counties of Transdanubia were Moson, Győr, Sopron, Vas, Zala, Veszprém, Fejér, Komárom, Esztergom, Somogy, Tolna and Baranya. They comprised the so called "Districtus Trans-Danubianus" from the beginnings of the 18th century. The boundaries of these counties, established by Stephen I of Hungary remained unchanged for almost 900 years until 1920.