“Curse Meroz!” said the angel of the Lord.
“Bitterly curse its inhabitants,
Because they came not to the aid of the Lord,
To the aid of the Lord among the warriors.”—Judges 5:23 (NJPS)
Wikipedia doesn't really help since there is no general consensus:
Thought to be a city within the plains of Galilee north of Mt. Tabor in Israel which was cursed by the angel of God in the song of Deborah and Barak; whose inhabitants did not come to help the Israelites in battle against Sisera's army. Meroz may possibly be identified with el-Murussus, a village about 5 miles Northwest of Beisan, on the slopes to the North of the Vale of Jezreel. The village of Kafr Misr has also been identified as a possible site, due its proximity to other nearby ancient sites such as Nein (Nain) and Indur (Endor).
Is it possible that it is a reference to Judah, Simeon, or Levi, which are not otherwise mentioned in the Song of Deborah?