Dumah

silence, (compare Ps. 94:17), the fourth son of Ishmael; also the
tribe descended from him; and hence also the region in Arabia
which they inhabited (Gen. 25:14; 1 Chr. 1:30).

There was also a town of this name in Judah (Josh. 15:52),
which has been identified with ed-Domeh, about 10 miles
southwest of Hebron. The place mentioned in the "burden" of the
prophet Isaiah (21:11) is Edom or Idumea.