In the X-XI century, on behalf the Roman Empire of Constantinople all the area was controlled and secured with trade duty rights, by powerful maritime city-state fleets of Genoa (with the clan of Vignolo de'Vignoli) and Venice (with the clan of Cornaros); When the Genoese managed to snatch a treaty from the Paleologos Emperors of Costantinople , they began invading portions of the Dodecanese, and other eastern isle from Chios to Rhodes which had remained under the nominal power of the Empire of Nicea; Genoese family clans (Moresco, Vignoli, Giustiniani, Spinola and others) each held some islands and they was granted to rule, trade and to exploit raw materials ("masticha", etc.), in exchange for maritime protection, while Orthodox monks ruled on Patmos and Leros. Finally, the Byzantine era came to an end when the islands were rented and sold by Genoeses for the venue of the Knights Hospitaller (Knights of St John): Rhodes was reinforced in 1309, and in the rest of the islands the Knights gradually built castles and fortress over the next few decades, while still the genoese fleet was in charge of the sea routes and kept their bases and trading stores ("Empori"). The Knights made Rhodes their stronghold, transforming its capital into a grandiose medieval city dominated by an impressive fortress, and scattered fortresses and citadels through the rest of the islands as well.