Some articles on tetrarchic:
Tetrarchy - Regions and Capitals
... These centres are known as the Tetrarchic capitals ... The four Tetrarchic capitals were Nicomedia in northwestern Asia Minor (modern Izmit in Turkey), a base for defence against invasion from the Balkans and Persia's ... years later and from uncertain sources), misunderstood the Tetrarchic system in this respect, believing it to have involved a stricter division of territories between the four emperors ...
... These centres are known as the Tetrarchic capitals ... The four Tetrarchic capitals were Nicomedia in northwestern Asia Minor (modern Izmit in Turkey), a base for defence against invasion from the Balkans and Persia's ... years later and from uncertain sources), misunderstood the Tetrarchic system in this respect, believing it to have involved a stricter division of territories between the four emperors ...