What is "romerike"

Romerike is a traditional district located north-east of Oslo, in what is today south-eastern Norway. It consists of the Akershus municipalities Fet, Lørenskog, Nittedal, Rælingen, Skedsmo, Sørum and Aurskog-Høland in the southern end ( Nedre Romerike), and Ullensaker, Gjerdrum, Nannestad, Nes, Eidsvoll and Hurdal in the northern end ( Øvre Romerike).