Latin word regere comes from Proto-Indo-European *rek-, and later Proto-Indo-European *h₃réǵeti (To be straightening, to be setting upright.)

Detailed word origin of regere

Dictionary entry	Language	Definition
*rek-	Proto-Indo-European (ine-pro)
*h₃réǵeti	Proto-Indo-European (ine-pro)	To be straightening, to be setting upright.
regere	Latin (lat)