In the early Islamic period to the Mongol invasion, due to climatic conditions and geographical strategic position, Masbadhan, as a part of the great province of Jibal in the western Iran, was in the center of attention of caliphs, sultans, princes and elders of the civil and military. Therefore, many socio-political events of the Muslim world happened in this geographical area. Many old geographical places of the region have disappeared or have been renamed in the future centuries, since the climatic conditions and geography of the area have changed, and then they are unfamiliar to readers. By a descriptive-analytic and through historical research, this article aims at introducing the geographical places of the Masbadhan region, as well as identifying the borders of the region during the Seljuqid period. This study shows that in the Seljuqid period, several important geographical places as Sirvan, Azivkhan, Mahaki Castle, Khulandjan Castle, and Al- Radh village were located in the area. Also, against the researchers who located the Bahar castle, near to Hamadan, this study shows that this castle as the capital of Kurdistan in the Ilkhanid period and the seat of Soleiman shah of Iveh, were located in the mountainous area of Masbadhan.
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