It was located on the Gelbes river,[1] not far from Prusa (modern Bursa in Turkey).

In earlier times it was called Helge, Helgas or Booscoete (Βοὸς κοίτη), Plin.

Modern scholars locate the town at the village of Tahtalı The city was taken by the Ottoman Empire in 1326 and the new Ottoman capital city was built at nearby Bursa (the Ancient Prusa).

In Byzantine times the town was the see of a suffragan of the Archdiocese of Nicomedia, in the sway of the Patriarchate of Constantinople.

It is vacant since decades, having had the following incumbents, so far of the fitting Episcopal (lowest) rank :