The latter five came as allies to the Valley of Siddim (that is, the Salt Sea).

Genesis 10:19
and the borders of Canaan extended from Sidon toward Gerar as far as Gaza, and then toward Sodom, Gomorrah, Admah, and Zeboiim, as far as Lasha.

Genesis 14:4
For twelve years they had been subject to Chedorlaomer, but in the thirteenth year they rebelled.

Genesis 14:8
Then the king of Sodom, the king of Gomorrah, the king of Admah, the king of Zeboiim, and the king of Bela (that is, Zoar) marched out and arrayed themselves for battle in the Valley of Siddim

Genesis 14:10
Now the Valley of Siddim was full of tar pits, and as the kings of Sodom and Gomorrah fled, some men fell into the pits, but the survivors fled to the hill country.

Numbers 34:12
Then the border will go down along the Jordan and end at the Salt Sea. This will be your land, defined by its borders on all sides."

Deuteronomy 3:17
The Jordan River in the Arabah bordered it from Chinnereth to the Sea of the Arabah (the Salt Sea) with the slopes of Pisgah to the east.

Joshua 3:16
the flowing water stood still. It backed up as far upstream as Adam, a city in the area of Zarethan, while the water flowing toward the Sea of the Arabah (the Salt Sea) was completely cut off. So the people crossed over opposite Jericho.

Psalm 107:34
and fruitful land into fields of salt, because of the wickedness of its dwellers.

All these were joined together in the vale of Siddim, which is the salt sea.