Boyd’s Bible Dictionary:

(rocky). (1) Mount and Land of Gilead, east of Jordan (Gen. 31:21-25; Num. 32:1; Josh. 17:6). (2) A mountain near Jezreel (Judg. 7:3). (3) Grandson of Manasseh (Num. 26:29-30). (4) Father of Jephthah (Judg. 11:1-2).

Concise Bible Dictionary:

The district on the east of the Jordan, extending from the river Yarmouk, a little south of the Sea of Galilee, to the north corner of the Dead Sea. It fell to the lot of Gad, except its northern part, which, where it joined Bashan, was possessed by Manasseh. It is a mountainous district, which accounts for some part of it being called “the mount of Gilead” in Genesis 31:21-25. Some of the mountains are 2,000 to 3,500 feet high, but from the west they look much higher because of the depression of the Jordan valley. Pasturage abounds in Gilead, and accounts for Gad and the others choosing it for their cattle. The district is divided into north and south by the river Jabbok (Zerka). The northern part is cultivated and has numerous villages; but the southern is mostly held by nomadic tribes, with but little cultivation, and having but one inhabited town now, called es Salt, 32° 2' N, 35° 42' E.
In the days of Ahab Ramoth-gilead was in possession of the Syrians, which was followed by all Gilead and Moab falling into their hands (1 Kings 22:3; 2 Kings 10:32-33). This was followed by Tiglath-pileser conquering the region, and carrying the Israelites into captivity (2 Kings 15:29; 1 Chron. 5:26). In the restoration of Israel their border eastward will extend to Damascus and Gilead (Ezek. 47:18). This ancient possession will thus be brought into blessing. The Ishmaelites who bought Joseph were traveling with balm and myrrh from Gilead (Gen. 37:25). The balm of Gilead was proverbial for its healing virtues (Jer. 8:22; Jer. 46:11).

Jackson’s Dictionary of Scripture Proper Names:

heap of witness: rolling forever