CELESIRIA (Κολπή Σύλφα = "hollow Syria"). Name given by the Greeks, after the conquest of Alexander the Great, to the region lying between Lebanon and Anti-Lebanon. At present it is called by the Arabs al-Baqā' (the valley). In Joshua (11:17; 12:7) mention is made of a valley or plain of Lebanon (Bīq'ath hal-Lēbhānōn), which seems to correspond to C. in the strict sense. In the region of Ba'albek, about 1176 m. above sea level, the rivers Nahr el-'Asī (Orontes) and Nahr el-Lītānī (Leontes) have their sources, which flow through C. toward the northeast and southwest respectively.
This region was the object of bitter contention between the Seleucids of Syria and the Ptolemies of Egypt. When Antiochus III, to settle the disputes, gave his daughter Cleopatra in marriage to Ptolemy V Epiphanes, king of Egypt, the Egyptians demanded that she bring as dowry C. and the neighboring regions (Judea, Samaria, Phoenicia). From the time when the Ptolemies became masters of most of Syria (192 B.C.), the name of C. was extended also to those southern regions. However, in the books of the Maccabees C. seems always distinct from Phoenicia (1 Macc. 10:60; 2 Macc. 3:5-8; 4:4; 8:8; 10:11).
After the Roman conquest (64 B.C.), Phoenicia and Samaria were separated from C., to which still belonged Iturea, Trachonitis, the Damascene, and Decapolis.