The lived in Ashteroth-karnaim in the time of Abram (Genesis 14:5). When the Philistines learned David was king, they spread out in the Valley of Rephaim and were defeated by the LORD like a flood. They returned, and the LORD led David from the rear and struck them down from Geba to Gezer.
Bible
War of Nine Kings, when Chedorlaomer's side defeated the Rephaim in Ashteroth-karnaim
Amraphel king of Shinar, Arioch king of Ellasar, Chedorlaomer king of Elam, and Tidal king of Goiim made war with Bera king of Sodom, Birsha king of Gomorrah, Shinab king of Admah, Shemeber king of Zeboiim, and the king of Bela (Zoar) in the Valley of Siddim (the Salt Sea). They had served Chedorlaomer for 12 years but rebelled in the 13th year. In the 14th year, Chedorlaomer's side defeated the Rephaim in Ashteroth-karnaim, the Zuzim in Ham, the Emim in Shaveh-kiriathaim, and the Horites in their hill country of Seir as far as El-paran on the border of the wilderness. Then they turned back for En-mishpat (Kadesh) and defeated all the country of the Amalekites and also the Amorites dwelling in Hazazon-tamar.
Abrahamic Covenant
When defining the land promised to Abram and his offspring, the Lord said, “To your offspring I give this land, from the river of Egypt to the great river, the river Euphrates, the land of the Kenites, the Kenizzites, the Kadmonites, the Hittites, the Perizzites, the Rephaim, the Amorites, the Canaanites, the Girgashites and the Jebusites.” (Genesis 15:18-21)
David vs the Philistines in the Valley of Rephaim
When the Philistines learned David was king, they came out, and David went down to the stronghold. They spread out in the Valley of Rephaim, so David inquired of the LORD whether he should go up and win, and he defeated them at Baal-perazim, the name taken from David's words that "The LORD has burst through my enemies before me like a bursting flood" and carried away their idols. Then, again, they came out in the Valley of Rephaim, and the LORD had David defeat them from the rear and come against them opposite the balsam trees. When he hears the sound of marching in the tops of the balsam trees, rouse himself, for the LORD has gone out before David's army to strike down the army of the Philistines. David obeyed struck them down from Geba to Gezer.
(2 Samuel 5)