Marcian of Heraclea (Μαρκιανὸς ὁ Ἡρακλεώτης) was a Greek geographer of the 4th or 5th century CE from Heraclea Pontica on the Black Sea [1][2]. A compiler and epitomizer rather than an original explorer, he had access to a significant library of earlier geographical texts. He is often associated with revising the work of Ptolemy and is distinguished by epithets like "the Younger" from an earlier, possibly homonymous, author [1][2].

His three known works are epitomes of earlier geographies. These include an Epitome of Menippus of Pergamon's Periplus of the Inner Sea, an Epitome of Artemidorus of Ephesus's Geography, and a two-book Periplus of the Outer Sea describing Atlantic and Indian Ocean coasts based on Ptolemy [1][2]. All survive only in fragments preserved in Byzantine manuscripts and the Suda lexicon [1][2].

Marcian’s significance lies in his role as a transmitter of knowledge. His compilations preserve summaries of now-lost Hellenistic and Roman geographical works, providing modern scholars with indirect evidence of earlier science and exemplifying the late antique scholarly tradition of epitomizing authoritative texts [1][2].

Sources 1. Encyclopædia Britannica: https://www.britannica.com/biography/Marcian-of-Heraclea 2. ToposText (citing the Suda and other fragments): https://topostext.org/people/1440