sentences:  Substantial parts of his work are derivative of Yaqut's "Mu'jam al-Buldan".Qazwini mentions fifty names as his sources, the most important of whom are old geographers and historians such as al-Istakhri, Ibn Fadlan, al-Mas‘udi, Ibn Hawqal, al-Biruni, Ibn al-Athir, al-Maqdisi, and al-Razi.Notwithstanding the fact that Qazwini's work is a compilation of known and unknown sources, it influenced later works of Islamic cosmology and Islamic geography through its style and language.