The king of Adullam was one of thirty-one rulers defeated in battle by Israel under Joshua (Joshua 12:7 - 24). When David became king he temporarily moved to an Adullam cave (called "the hold" in 2Samuel 5:17) to prepare battle plans against the Philistines.
Ashdod (Azotus)
Ashdod was one of the five major cities in Philistine territory located next to Israel (Joshua 13:3). It was also one of the cities that was humorously punished by God for storing the Ark of the Covenant (1Samuel 5).
Ashdod, in the New Testament, is referenced as Azotus (Acts 8:40). Philip was miraculously transported to the city after he baptized an Ethiopian eunuch (Acts 8).
Ashkelon
Ashkelon was one of the five major cities controlled by the Philistines (Joshua 13:3). Samson slew thirty men, by himself, in the city (Judges 14:19)!
Azekah
Joshua and the children of Israel had defeated a coalition of rulers led by the king of Jerusalem. As the enemy was fleeing God chose to rain down large stones (hailstones?) upon their heads at Azekah. This intervention was so successful that the Lord killed more of the enemy with stones than the Israelites did with swords (Joshua 10:5 - 11)!
Beersheba
During most of Israel's history, the phrase "Dan to Beersheba" was commonly used to designate the northern and southern limits of the nation's territory (Judges 20:1, 1Samuel 3:20, 1Kings 4:25, 2Chronicles 30:5).
Bethlehem
Tradition has Rachel, the much beloved wife of Jacob, buried near the northern entrance of modern Bethlehem (Genesis 35:15). The events of the book of Ruth, one of only two Biblical books penned by women, take place near the city (Ruth 1:1 - 2). In addition, of course, both King David and Jesus Christ were born in Bethlehem (John 7:42).
Debir
Debir, located in Judah's territory southwest of Hebron, was designated a Levitical city (Joshua 21:15).
Eglon
The king of Eglon was one of the thirty-one rulers conquered by Joshua (Joshua 12:12).
Engedi
Chedorlaomer, who waged the Bible's first war, conquered and plundered Hazazon-tamar (Engedi) along with many other cities (Genesis 14:5 - 7). King David used Engedi as a stronghold to evade capture by King Saul (1Samuel 23:29).
Gath
Gath was one of the five major Philistine centers of power (Joshua 13:3). The city was home to a race of giants called the Anakim (11:22). The greatest giant who lived in Gath was Goliath, the man who challenged Israel and King David to kill him in battle (1Samuel 6:17, 17:4).
Gaza
Samson, after utilizing the services of a whore, broke off Gaza's city gates and carried them to the top of a hill near Hebron! At Gaza, he also made his last stand for God by killing himself along with several thousand Philistines (Judges 16).
Gedor
Gedor, once occupied by the Amalekites, was given to Israel's tribe of Judah as an inheritance in the Promised Land.
Gerar
Gerar was one of the lesser cities under the control of the Philistines. It was conquered by God's people during the reign of Judah's King Asa (2Chronicles 14:13 - 14).
Hebron
The city of Hebron included an area named Mamre where Abraham lived (Genesis 13:18). A nearby cave was used as a burial location for him, Sarah and other members of the family (Genesis 23:2, 19, 25:9, 35:29, 49:31, 50:13).
David, at Hebron, was anointed ruler over Judah and Benjamin then later over all Israel (2Samuel 2:1 - 3, 11, 5:1 - 5). He ruled from Hebron until the capital was relocated to Jerusalem.
Hormah
The king of Hormah, after Israel crossed the Jordan River to battle for their inheritance, was one of thirty-one city rulers conquered by Joshua (Joshua 12:14).
Lachish
King Sennacherib of Assyria was attacking Lachish in 701 B.C. when he sent his general and 185,000 troops to demand Jerusalem's surrender. His attempt to take the capital from King Hezekiah would result in the worst military defeat in human history! All his troops around Jerusalem were killed in a single night by God's death angel (2Kings 18 - 19).