It is widely accepted that the fall of Constantinople in 1204 brought to its knees an empire already on the point of collapse, notably on its Balkan fringes, where three peoples showed new vigour: the Bulgarians, the Serbs and the Albanians. The boundaries between their lands were still very fluid, especially those between Bulgaria and Serbia, and each was at a different stage of evolution towards political and cultural autonomy. Bulgaria under the Asen dynasty, which broke with the Byzantines in 1185–7 and which in 1202 gained Byzantine recognition of its mastery over the lands from Belgrade to Sofia, represented the resurgence of an older state, though with rather different territorial boundaries. Even after two centuries of Byzantine dominance, Bulgaria retained distinctive political and cultural traditions which sustained its self-image as the major power in the Balkans, and, in consequence, implied Bulgarian rights over Constantinople itself.