Pentapolis

A pentapolis, from the Greek words penta 'five' and polis 'city(-state)' is geographic and/or institutional grouping of five cities.

in the biblical Holy Land, the word, occurring in Wisdom, x, 6, designates the region where five cities — Sodom, Gomorrha, Segor (A. V., Zoar), Adama and Seboim — united to resist the invasion of Chodorlahomor (Genesis, xiv), and of which four were shortly after utterly destroyed. (see: Catholic Encyclopaedia)
in the Roman province of Libya Superior (the western part of Cyrenaica until Diocletian's Tetrarchy reform in 296AD), five Mediterranean coastal cities (east of it was Marmarica, which became Libya inferior province): the eponymous capital Cyrene and its port Apollonia, Ptolemais (the next capital after Cyrene's destruction by an earthquake), Barca (the later Arab provincial capital Barka) and Berenica (modern Benghazi); also known as the Pentapolis inferior ('lower P.')
the medieval Central-Italian Pentapolis on the Adriatic, atypically, actually was one duchy east of Tuscany and north of the duchy of Spoleto, including the port cities (West to East) of Rimini, Pesaro, Fano, Sinigaglia and Ancona, formerly south of the Byzantine secular Exarchate of Ravenna, later transformed into the March of Ancona
the Philistine Pentapolis: Ashkelon, Ashdod, Ekron, Gath, and Gaza
the Doric - or Dorian Pentapolis: Kos, on the island of the same name in the Aegean Sea; Cnidus, in Caria on the west coast of Asia Minor; Lindus, Ialysus and Camirus, all three on Rhodes.

Not to be confused with a homonymous port city in Bengal ? northern Burma

many occurrences in the Catholic Encyclopaedia
Westermann Großer Atlas zur Weltgeschichte ('Great Atlas of World History', in German)

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