Mudbrick and earthen architecture in the Middle East, particularly in Iran, has a long-standing ‎tradition ‎and remarkable continuity due to the arid climate and the abundance of soil ‎sediments. Archaeological ‎evidence from eastern and southeastern Iran, including the Sistan ‎region and sites such as Shahr-e ‎Sukhteh, Dahaneh-ye Gholaman, and Old Zahedan ‎‎(Zahedan-e Kohneh), demonstrates the persistence ‎of this technology from prehistoric times ‎through the Islamic periods. Despite this extensive ‎background, detailed laboratory studies ‎on the materials of historical mudbrick and earthen buildings in ‎this region remain ‎limited.The aim of this research is to identify the structure and determine the chemical ‎composition of historical ‎mudbricks from the Islamic period in the rabad area of Zahedan-e ‎Kohneh‎, in order to provide a ‎scientific basis for assessing material conditions and ‎supporting conservation and restoration decision-‎making for earthen architecture. To this ‎end, a set of historical mudbrick samples from the Afghan ‎Tower area was examined using ‎standard laboratory techniques, including X-ray fluorescence (XRF), X-‎ray diffraction (XRD), ‎titration analysis, and gravimetric determination of sulfate content.‎The results indicate that ‎the mudbricks were produced from local, alluvial, and heterogeneous soils with ‎a clay–‎siliceous composition containing carbonate and gypsum lenses. The presence of mineral ‎phases ‎such as quartz, feldspars, calcite, dolomite, muscovite, and montmorillonite, together ‎with a wide ‎dispersion of calcium carbonate (9–40.5%) and calcium sulfate (0.26–1.4%), ‎reflects the heterogeneity of ‎the original material composition and the potential reactivity of ‎the materials in response to moisture ‎and salt-related factors.‎The findings underscore the ‎necessity of considering conservation constraints and conducting ‎supplementary ‎investigations and tests prior to any consolidation interventions. By providing chemical ‎and ‎mineralogical data, this study establishes a preliminary framework for the scientific support of ‎‎conservation and restoration decision-making for earthen buildings in the region and ‎highlights the ‎critical role of material composition analysis in evaluating their stability ‎conditions.‎