Over a hundred Hebrew ostraca were found during excavations at "upper" Tell Arad. The "upper" site of Arad has seven strata spanning the Iron age, but most of the readable ostraca were found in the last two layers, VII and VI. There dating of the archaeological strata done by Aharoni has been contested by others, but this often puts them in conflict with the paleographic dating giving to the letters from these strata. Most of the letters seem to come from the late 7th and early 6th century, the twilight of the southern kingdom. A number of letters paint Arad be a "fortified supply depot" that dispatched supplies and troops to the military outposts where needed. A number of the letters are addressed to or concern Elyashib, who was an official or administrator at the sight. Edom is specifically mentioned as a military threat in the letters. It is assumed that these letters are roughly contemporary with the Lachish letters, when Judah was under the looming shadow of Babylonian invasion. Elyashib's name is attested in both layers VII and VI, showing that even through the site was destroyed, it was quickly reoccupied again by Judahites.
ABD I:331-337; COS II; Lindenberger, Ancient Aramaic and Hebrew Letters, p. 114-115