Reference: Shephelah
Fausets
Hebrew for KJV "the vale," "the plain," "the low country"; rather, as 1Ma 12:38 proves, the low hills between the central mountains and the seacoast plain, compare Seville; for Adida on the shephelah answers to Haditheh, which is not in the plain but the low hills. The valleys amidst the shephelah are seldom more than 300 ft. deep, and the slopes much more gradual. Eusebius says that the country about Eleutheropolis was still called shephelah. It is the district of rolling hills, not spurs or shoulders from the main range, but between this and the plain below.
The article is always prefixed, the shephelah (ha-Shephelah), a "marked physical feature of the land"; like our phrase "the downs," "the wolds" (Zec 7:7; Jos 15:33; De 1:7). The divisions are mountain, "hill" shephelah, and plain (Talmud, tract Shevith). Rabbi Jochanan says that from Bethhoron to Emmaus is "mountain" (har); from Emmaus to Lydda hill; and from Lydda to the sea plain. In Jos 15:33-47 the shephelah contains 42 cities with their dependent hamlets, many of them in the mountains. The shephelah is most fruitful, receiving, as it does, the soil washed down from the mountains behind by the winter rains; and here were extensive tracts of grain land, the references to which and to the flails and other agricultural instruments are frequently met with.