[Sidenote: State of the Empire, 659.] When he took stock of his realm, Constantinus found that in the East five great districts were irretrievably lost: the nearer half of the exarchate of Africa, from Tripoli to the Libyan desert, Egypt, Syria, and the greater part of Roman Armenia had fallen into the power of Saracens. Moreover, in Europe, the troubled years between 610 and 659 had brought about the complete loss of the inland parts of the Balkan peninsula. The Slavs, whose incursions had already grown so dangerous in the reign of Maurice, had now obtained complete possession of the whole of Moesia, and of the inland parts of Thrace and Macedon. Their settlements extended to within a few miles of the gates of Adrianople and Thessalonica, both of which cities they from time to time besieged without success. They had even encroached south of Mount Olympus, and thrust forward their colonies into some parts of Greece. The imperial dominions were restricted to a coast-slip running all round the peninsula, from Spalato in Dalmatia to Odessus on the Black Sea. In the West we have seen, while detailing the history of the Lombards, that the East-Romans now preserved only the exarchate of Ravenna, the duchies of Rome and Naples, the southern point of Italy, and the islands of Sicily and Sardinia. Recognising that he must look to reorganisation rather than to reconquest for restoring the strength of the empire, Constantinus devoted himself to securing his borders. The moment that the civil war of the Arabs broke out, and left him free to move elsewhere, he marched against the Slavs of the Balkans, defeated them, and reduced them to pay tribute. It was hopeless to dream of driving them back across the Danube, and the emperor was contented to accept the existing state of things, and to secure the coastland of Thrace and Macedonia from further molestation, by imposing a line of demarcation between the Slavonic tribes and the much-reduced provinces (657-8).