sea as their principal highway.
They transported to the islands of the Mediterranean as well as the
coast of Northern Africa and Southern Europe heavy cargoes consisting of
the product of their own skill and industry as well as of the manifold
exports of the east. They sailed even beyond the "Pillars of Hercules"
into the Atlantic Ocean and the North Sea. Through their hands "passed
the gold and pearls of the east and the purple of Tyre, slaves, ivory,
lion and panther skins from the interior of Africa, frankincense from
Arabia, the linen of Egypt, the pottery and fine wares of Greece, the
copper of Cyprus, the silver of Spain, tin from England, and iron from
Elba."

But while the Phoenicians for their commercial intercourse with other
nations relied chiefly upon the sea, the great highway of nature, they
neglected by no means road-building at home. They connected their great
cities, Sidon and Tyre, by a coast road, which they extended in time as
far as the Isthmus of Suez. They also established great commercial
routes by which their merchants penetrated the interior of Europe and
Asia. Caravan roads extended south to Arabia and east to Mesopotamia and
Armenia, penetrating the whole Orient as far as India, and even the
frontiers of China. The Phoenicians thus became the traders of
antiquity, Tyre being the link between the east and the west.

The Persian Empire, which under Darius stretched from east to west for a
distance of 3,000 miles and comprised no less than two million square
miles, with a population of seventy or eighty millions, had, with the
exception of the Romans, perhaps the best system of roads known to
ancient history. Indeed, it is doubtful whether without it such a vast
empire, more than half as large as modern Europe, could have been held
together. Each satrap, or prefect of a province, was obliged to make
regular reports to the king, who was also kept informed by spies of what
was taking place in every part of the empire. To aid the administration
of the government, postal communication for the exclusive use of the
king and his trusted servants connected the capital with the distant
provinces. This postal service was, four or five centuries later,
patterned after by the Romans. From Susa to Sardes led a royal road
along which were erected caravansaries at certain intervals. Over this
road, 1,700 miles long, the couriers of the king rode in six or seven
days. Under Darius the roads of the empire were