The geomagnetic field variations during the Iron Age (last 1200 years BC) are poorly constrained for Bulgarian territory due to the scarcity of archaeological sites with a well-established chronology. Additionally, the collected Iron Age materials frequently fail to provide reliable archaeointensity data. In an effort to expand the Bulgarian archaeomagnetic database for the last millennia BC and to find an explanation for the low success rate of Thellier experiment, 28 baked clay structures from 10 archaeological sites were archaeomagnetically studied. Magnetically soft minerals dominate in all collections despite the variety of the sampled structures (hearths, domestic ovens, ovens, pottery kilns, burnt dwelling remains, mud-bricks), which suggests differences in the ancient firing conditions. The main carriers are magnetite/titanomagnetite and/or maghemite/titanomaghemite. Verwey transition is well expressed in most samples. Usually more than one magnetic phase exists and noticeable mineralogical transformations occur during laboratory heating. Regardless of all the pre-selection criteria applied, the total success rate of intensity determination is quite low (21%), which seems to be typical for Bulgarian Iron Age materials. At this epoch that starts with a significant decline in the quality of material culture, combustion structures are usually poorly preserved, short-term used (frequently only once) and heated to temperatures around and below 600 °C. A clear relationship is observed between median destructive temperature and success of intensity determination, which suggests that this parameter have a potential as a pre-selection criterion.

The new data double the Bulgarian archaeomagnetic dataset for the period in concern with 18 directional and 7 intensity results (6 full vectors). An inclination and intensity decrease is outlined at around 400 BC with assumed variation rates 0.10°/year and 0.32 μT/year, respectively. Considering the whole database, three intensity peaks are detected at circa 1050 BC (Fa ~ 78 μT), 550–500 BC (Fa ~ 96 μT) and 300 BC (Fa ~ 80 μT). The second peak is the highest over the entire eight-millennium long Bulgarian archaeomagnetic record. The first half of the Iron Age (1200–600 BC) is characterized with easterly declinations reaching ~18°E around 1150 BC, while in the last half it turns westerly with westernmost values around 400 BC. The current state of Bulgarian archaeomagnetic reference curves for the Early Iron Age is not sufficient for precise archaeomagnetic dating. Although the resulting dating interval for Ryahovets oven (the only structure with uncertain archaeological dating) coincides with the archaeological evidence, it spans more than 200 years. In such a case, correlation with other archaeomagnetically studied sites from the corresponding period can be especially helpful.

由于缺乏具有完善年表的考古遗址，铁器时代（公元前 1200 年）的地磁场变化对保加利亚领土的限制很差。此外，收集到的铁器时代材料经常无法提供可靠的考古强度数据。为了扩大公元前最后一千年的保加利亚考古磁数据库，并为 Thellier 实验的低成功率找到解释，对来自 10 个考古遗址的 28 个烘烤粘土结构进行了考古磁学研究。尽管采样结构（炉膛、家用炉、烤炉、陶窑、烧毁的住宅遗迹、泥砖）各不相同，但软磁性矿物在所有收藏中都占主导地位，这表明古代烧制条件存在差异。主要载体是磁铁矿/钛磁铁矿和/或磁赤铁矿/钛磁铁矿。Verwey 转变在大多数样本中得到了很好的表达。通常存在不止一种磁性相，并且在实验室加热期间会发生显着的矿物学转变。无论采用何种预选标准，强度测定的总成功率都非常低（21%），这似乎是保加利亚铁器时代材料的典型特征。在这个以物质文化质量显着下降开始的时代，燃烧结构通常保存不佳，被短期使用（通常只使用一次）并加热到 600 °C 左右或以下的温度。在中值破坏温度和强度确定的成功之间观察到明显的关系，

新数据是保加利亚古地磁数据集的两倍，涉及 18 个方向和 7 个强度结果（6 个完整矢量）。公元前 400 年左右的倾角和强度下降被概述，假设变化率分别为 0.10°/年和 0.32 μT/年。考虑到整个数据库，在大约 1050 BC (Fa ~ 78 μT)、550–500 BC (Fa ~ 96 μT) 和 300 BC (Fa ~ 80 μT) 检测到三个强度峰值。第二个峰值是整个八千年保加利亚古地磁记录中最高的。铁器时代的前半段（公元前 1200-600 年）的特征是东偏角在公元前 1150 年左右达到 ~18°E，而在后半段它转向西风，最西值在公元前 400 年左右。保加利亚早期铁器时代古地磁参考曲线的当前状态不足以进行精确的古地磁测年。尽管由此得出的 Ryahovets 烤箱（唯一具有不确定考古年代的结构）的测年间隔与考古证据相符，但它跨越了 200 多年。在这种情况下，与相应时期的其他古地磁研究地点的相关性可能特别有用。