Ashkalon is first mentioned in the Egyptian Execration Texts of the 11th Dynasty (c. 20th-19th century) as Asqanu. It also appears in several Tell el-Amarna letters (EA, 287, 320-2, 370). Although it seems to have remained loyal to Egypt on the whole (EA, 320, 322), Abdihiba, the ruler of Jerusalem, complained to Pharaoh that the people of Ashkalon helped the Habiru, Egypt's enemy (EA, 287:14-16). About 1280 BCE Ashkalon rebelled against Ramases II, who put down the rebellion; the conquest is depicted on the Karnak temple. It was again captured by Pharaoh Mernaptah approximately 1220 BCE, as indicated in his "Israel Stele". Ashkalon is also mentioned in an ivory tablet from Magiddo. Toward the middle of th 12th century BCE it was taken by the Philistines and was thereafter one of their Pentapolis (Josh 13:3; I Sam. 6:17; II Sam. 1:20). According to Judges 1:18, the tribe of Judah conquered Ashkalon together with Gaza and Ekron (cf., however, Judges 1:18 in the Septuagint, which states that Ashkalon, gaza and Ekron were not taken). Ashkalon is mentioned in connection with several details of the Samson stories (Judges 14:19). During the period of the monarchy, it continued to be one of the main Philistine cities and ports (II Sam. 1:20), and Amos predicted its punishment (Amos 1:8). It was brought under Assyrian suzerainty by Tiglath-Pileser III in 734 BCE. Sidquia, king of Ashkalon, was one of the participants in Hezekiah's rebellion against Assyria. In Sennacherib's account of his campaign in 701 BCE, he describes the capture of some of Sidqia's cities in the vicinty of Jaffa, Ashkalon's submission, and the deportation of its king (Sennachrib Prism, 1:50ff.). With the collapse of Assyrian rule, Ashkalon fell into the hands of Psammetichus and Necho of Egypt. The city was subdued and destroyed by Nebuchadnezzar (Jer. 47:5-7).
In the Persian period, Ashkalon was under the control of Tyre (according to Pseudo-Scylax. 4th c. BCE). with the division of Alexander's empire, Ashkalon was included in the Ptolemies' domain. A Jewish community flourished in the city under their rule. Ashkalon subsequently fell into the hands of Antiochus III and became an important center of Greek civilization in Hellenistic times. It regained its independence in 104 BCE and remained independent throughout the reigns of the Hasmoneans rulers, Hyrcanuss and Alexander Yannai. In the Roman period it was considered a "free and allied city". Although not included in the territory ruled by Herod, he nevertheless built market places and public baths there and adorned the town with gardens--perhaps because it was his birth place. During the war against the Romans (66CE), the Ashkalonites clashed with the Jews and defeated them. In the period of the Mishnah and the Talmud, Jews lived in Ashkalon, as the remains of a synagogue from that period show. Talmudic sources mention its ordeals and its fair (TJ, Shev. 6:1; 36c; Sif. Deut. 51). In the early years of the Byzantine period, Ashkalon was the seat of a school of Hellenistic philosophy and was strongly opposed to Christianity. The population adhered to the worship of its fish-goddess Dercato (Atargatis), whose image consisted of the head and trunk of a woman and the tail of a fish and whose temple contained pools for sacred fish (Diodorus, 2:4; Pausanias, 1:14,16).
Encyclopaedia Judaica, Jerusalem, 1971