Economically, sea-borne trade with the Middle East was cut off by the mainland Greeks and Magna Graecia boycotted Carthaginian traders. This led to the development of trade with the West and of caravan-borne trade with the East. Gisco, son of Hamilcar was exiled, and Carthage for the next 70 years made no recorded forays against the Greeks nor aided either the Elymians/Sicels or the Etruscans, then locked in struggle against the Greeks, or sent any aid to the Greek enemies of Syracuse, then the leading Greek city in Sicily. Based on this abstinence from Greek affairs, it is assumed that Carthage was crippled after the defeat of Himera. Focus was shifted on expansion in Africa and Sardinia, and on the exploration of Africa and Europe for new markets. The grandsons of Mago I, Hannibal, Hasdrubal and Sappho (sons of Hasdrubal), together with Hanno, Gisco and Himilco (sons of Hamilcar) are said to have played prominent parts in these activities, but specific details of their roles are lacking. By 450 BC, Carthage had finally stopped paying tribute to the Libyans, and a line of forts was built in Sardinia, securing Carthaginian control over the island coastline. Hanno, son of Hamilcar may be the famous Hanno the Navigator, which places his expedition around 460–425 BC, and Himilco may be the same as Himilco the Navigator, which puts his expedition sometimes after 450 BC. Hanno the Navigator sailed down the African coast as far as Cameroon, and Himilco the Navigator explored the European Atlantic coast up to Britain in search of tin. These expeditions took place when Carthage was at the zenith of its power. If Hanno and Himilco are indeed related to Mago, then Carthage had recovered quite rapidly from her "crippled" state. If Hanno and Himilco are not of the Magoniod family, then these expeditions may have taken place before 500 BC and Carthage might have been crippled for 70 years. Carthage took no known part in the activities of the Sicilian chief Ducetius in Sicily against Syracuse, nor in the wars between Akragas and Syracuse, or the battles of the Etruscans against Syracuse and Cumae. Carthage's fleet also took no recorded part in the shattering defeat of the Etruscan fleet at the naval Battle of Cumae in 474 BC at the hands of the Greeks.