Hemath
"Hemath" is an older spelling that gathers two distinct entries in the UPDV: a place better known as Hamath, and a personal-name Hammath who fathers the house of Rechab.
Hemath as the Northern Boundary (Hamath)
In Amos's threat against the apostate Northern Kingdom, the conqueror's reach is described in geographic extremes — from the far north to the far south of the land: "For, look, I will raise up against you⁺ a nation, O house of Israel, says Yahweh, the God of hosts; and they will afflict you⁺ from the entrance of Hamath to the brook of the Arabah" (Amos 6:14). The UPDV uses "Hamath" rather than the older "Hemath," but the place is the same — the standard northern-boundary marker of the land.
Hemath, Father of the House of Rechab
A separate figure — a person, not a place — appears in the Chronicler's genealogy of Judah's families: "And the families of scribes who dwelt at Jabez: the Tirathites, the Shimeathites, the Sucathites. These are the Kenites who came of Hammath, the father of the house of Rechab" (1 Chr 2:55). Here UPDV spells the name "Hammath." He is the ancestor from whom the Kenite scribal families and the Rechabite house descend.