The marriages of those born in the porphyry, as members of the Byzantine imperial house, with the princes and princesses of the Slavic countries of the Balkans, are the best prosopographical reflection of the evolution of the relationships between the Empire of the Romans with their immediate neighborhood in the Balkans. During the second half of the Byzantine millennium (10th–15th centuries), these matrimonial alliances increased, with substantially similar numbers as regards marriages with the Bulgarian and the Serbian dynasties, except that the Byzantino-Bulgarian marriages were earlier chronologically, while the Byzantino-Serbian ones were more numerous towards the end of the Empire, occurring right up until the last emperor Constantine XI, himself the offspring of an imperial marriage with a Serbian princess.