PELUSIO (Hebr. Sin, Septuagint [Ex. 30:15] Σλίν; Vulg. Pelusium, Coptic Peremlin). — Ancient Egyptian city, situated at the easternmost branch of the Nile, corresponding to the present-day plain of et-Tineh. Since, by virtue of its position, it was the key to Egypt, it was important commercially and militarily. Both the caravans and the armies disputing the territories of Africa and Asia stopped at P.
During the Roman period P. was embellished with buildings, among which the temple of Zeus Casis is noteworthy; it bears a monumental dedicatory inscription to Hadrian. Pompey was killed at P.; the astronomer Ptolemy was born there. During the Christian period there was considerable monastic development; in a monastery at P. lived St. Isidore (v.) known as the Pelusiot. With the Muslim conquest in 639, the city declined.