B. Spuler, "Central Asia in the Mongol and Timurid periods", published in Encyclopædia Iranica, Online Edition, 2006/7, (LINK): "... Like his father, Olōğ Beg was entirely integrated into the Persian Islamic cultural circles, and during his reign Persian predominated as the language of high culture, a status that it retained in the region of Samarqand until the Russian revolution 1917 [...] Ḥoseyn Bāyqarā encouraged the development of Persian literature and literary talent in every way possible ..."