Greater Khorasan
The region of Herat was historically part of Greater Khorasan, which was successively controlled by the Tahirids followed by the Saffarids, Samanids, Ghaznavids, Ghurids, Ilkhanates, Timurids, Safavids, Hotakis, Afsharids, Durranis, Qajarids until it became part of the modern state of Afghanistan.