According to Vladimir Minorsky: "The presence of Iranian settlers in Transcaucasia, and especially in the proximity of the passes, must have played an important role in absorbing and pushing back the aboriginal inhabitants. Such names as Sharvan, Layzan, Baylaqan, etc., suggest that the Iranian immigration proceeded chiefly from Gilan and other regions on the southern coast of the Caspian."[6] Abu al-Hasan Ali ibn al-Husayn Al-Masudi (896–956), the Arab historian states Persian presence in Aran, Bayleqan, Darband, Shabaran, Masqat and Jorjan.[7] From the 9th century, the urban population of Shirwan increasingly spoke Persian,[8][9] while the rural population seems to mostly have retained their old Caucasian languages. Up to the nineteenth century, there was still a large number of Tat people (who claim to be descendants of Sassanid era Persian settlers), however due to their similar culture and religion with the Turkic-speaking Azerbaijanis, this population was partly assimilated.[10]