The Jasper Sea: Ancient Name for the Caspian Sea

The Jasper Sea (Mare Iaspis in Latin) was the name given by the 1st-century AD Roman geographer Pomponius Mela to what we now call the Caspian Sea.

Historical Context

In his work De situ orbis libri III (~43 AD), Mela described the Caspian as:

• "Green in colour" (viridi colore) — likely from phytoplankton blooms, suspended sediments, or mineral reflectance in the shallow northern basin.
• Named for jasper — a green variety of chalcedony (microcrystalline quartz) prized in antiquity. The stone's color matched the sea's appearance.
• Connected to "Ocean" — Mela believed it flowed into the northern ocean (incorrect; it's endorheic).

Other Ancient Names

• Hyrcanian Sea (Hyrcanum Mare) — after Hyrcania (region south of Caspian)
• Caspian Sea — from Caspii tribe (ancient inhabitants of western shores)
• Alban Sea — from Caucasian Albania (eastern shores)
• Khazar Sea — medieval Arabic/Persian (Bahr al-Khazar), after Khazar Khaganate
• Khvalyn Sea — Old East Slavic, after Khvalis (Khwarezm)

Modern Caspian Sea

World's largest inland water body (371,000 km²), bordered by Russia, Kazakhstan, Turkmenistan, Iran, Azerbaijan. Endorheic, brackish (1.2% salinity), vast oil/gas reserves, sturgeon caviar, water level fluctuations (±2 m/decade). The "Jasper Sea" name faded as geographic knowledge advanced—but Mela's observation of its green hue remains accurate for the northern shallow waters today.