The frequent, and perhaps sometimes confusing references to the various historical eras throughout the travelogue, prompted me to include the following historical time line which may be useful particularly for the entries on Turkmenistan and Iran.

Elamites & Medes (Persia)   

Archaemenid Empire (Persia) - First Persian Empire. Cyrus The Great, Darius, Xerxes etc

Years of Alexander the Great (Invasion of Persia and Central Asia)

Seleucid Era ("Hellenisation" of Persia)

Parthian Empire (Persia)

Sassanid Empire (Second Persian Empire)

Arab Conquests and Introduction of Islam (Persia and Central Asia)

The Samanids (Central Asia)

Seljuk Turks (Persia)

The Mongols - Genghis Khan (Persia and Central Asia)

Marcos Polo's Journeys

Tamerlame (Central Asia)

Safavid Empire (Third Persian Empire)

Qajar Dynasty (Persia)

Russian Invasion of Central Asia

Russian Revolution

Pahlavi Era (Persia)

Ashgabat Destroyed by Earthquake (Turkmenistan)

Islamic Revolution and Ayatollah Khomeini Comes to Power (Iran)

USSR Invades Afghanistan

Iran-Iraq War

President Niyazov (Turkmenbashi) Comes to Power (Turkmenistan)

Ayatollah Khomeini Dies and Replaced by Ali Khamenei (Iran)

Collapse of Soviet Union and Formation of Commonwealth of Independent States (CIS)

President Khatami is Elected (Iran)