How was the Persian Empire able to link the territories in its
empire, and how far did the
empire reach?

The Persian kings — especially Cyrus and, later, Darius I (522-486 B.C.E.) Cyrus built the foundations of a courier, or mail, system. Darius I built a communication network that connected most of the empire. A 1,600-mile-long royal road was built from Sardis to Susa, one of the administrative capitals.It varied over the years as it lost and gained land. However, at its greatest extent, under the Emperor Trajan in AD116/7, it covered 6,500,000 km² of land and stretched from Britain and Portugal through Europe to modern-day Azerbaijan and Iraq, to the Caspian Sea and the Persian Gulf.

Explanation:

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