18th c., 1720–1818), found in many mixed Ukrainian–Russian and Russian–Ukrainian texts. Modern Ukrainian (MoU, from the very end of the 18th c., or , from 1818), the vernacular recognized first in literature, and subsequently all other written genres. Ukraine annually marks the Day of Ukrainian Writing and Language on November 9, the Eastern Orthodox feast day of Nestor the Chronicler. History of the spoken language Rus and Kingdom of Ruthenia During the Khazar period, the territory of Ukraine was settled by Iranian (post-Scythian), Turkic (post-Hunnic, proto-Bulgarian), and Uralic (proto-Hungarian) tribes and Slavic tribes. Later, the Varangian ruler Oleg of Novgorod would seize Kyiv and establish the political entity of Kievan Rus'. The era of Kyivan Rus is the subject of some linguistic controversy, as the language of much of the literature was purely or heavily Old Church Slavonic. Literary records from Kyivan Rus testify to substantial difference between Russian and Ruthenian form of the Ukrainian language as early as Kyivan Rus time. Some theorists see an early Ukrainian stage in language development here, calling it Old Ruthenian; others term this era Old East Slavic. Russian theorists tend to amalgamate Rus to the modern nation of Russia, and call this linguistic era Old Russian. However, according to Russian linguist Andrey Zaliznyak, Novgorod people did not call themselves Rus until the 14th century, calling Rus only Kyiv, Pereiaslav and Chernihiv principalities (the Kyivan Rus state existed till 1240). At the same time as evidenced by the contemporary chronicles, the ruling princes of Kingdom of Ruthenia and Kyiv called themselves "People of Rus" – Ruthenians, and Galicia–Volhynia was called the Kingdom of Ruthenia. Also according to Andrey Zaliznyak, the Novgorod dialect differed significantly from that of other dialects of Kyivan Rus during the 11th–12th century, but started becoming more similar to them around 13th–15th centuries. The modern Russian language hence developed from the fusion of this Novgorod dialect and the common dialect spoken by the other Kyivan Rus, whereas the modern Ukrainian and Belarusian languages developed from the dialects which did not differ from each other in a significant way. Under Lithuania/Poland, Muscovy/Russia and Austro-Hungary After the fall of Kingdom of Ruthenia, Ukrainians mainly fell under the rule of Lithuania and then Poland. Local autonomy of both rule and language was a marked feature of Lithuanian rule. In the Grand Duchy of Lithuania, Old East Slavic became the language of the chancellery and