The dragon was an emblem adopted by Briton chiefs as their emblem or symbol of authority and 'pendragon' meant high chief (top honcho). There were a lot of old titles which can be difficult to keep track of and differentiate precisely: leader (wledig), emyr (emperor), and king (but there were often many of having these titles, so the territory controlled by them was often not very large. There were also a few derivatives of older Roman titles, Dux/Duke, etc,.