The mugni (archlute) is a Persian stringed musical instrument which resembles a tar except that the two globes are connected and not separated like the tar's. During Ghuri rulers and Khwarizmi (12th – 13th century) music grew. Two notable theorists of this era were Fakhr al-Din al-Razi and Nasir al-Din al-Tusi. Another Persian theorist was Qutb al-Din al-Shirazi who was famous for Pearl of Crown (Durrat al-taj). In the Treasure-House of Gift (Kanz al -Tahaf) an important work in 1350, ud (lute), rubab (lute), mughni (archlute), chang (harp), nuzhe, qanun (psaltery), Ghaychak (spiked viol), pisha (fife) and (reedpipe) are completely described. In other places, dutar (two strings) and setar (three strings) exquisite of poet Hafez are mentioned.