During the Middle Ages, the position of Tigray Mekonnen ("Governor of Tigray") was established to rule over the area. Other districts included Akele Guzay (now part of Eritrea), and the kingdom of the Bahr negus, who ruled much of what is now Eritrea and Shire district and town in Western Tigray. At the time when Tigray Mekonnen existed simultaneously with that of Bahr negus, their frontier seems to have been the Mareb River, which is currently constitutes the border between the Ethiopian province of Tigray and Eritrea.