The Volhynians (Волиняни, Volyniany, Wołynianie) were an East Slavic tribe of the Early Middle Ages and the Principality of Volhynia in 987–1199. Russian historiography on regions like Volhynia, specifically before the emergence of the Soviet Union in 1922, brought together Eastern European lands as justification for Romanov rule. From this two branches of historiography can be traced into the 20th century. The split stems from different arguments surrounding the stability of the Kievan Rus' prior to the Mongol Invasion in the 13th Century. Solov'ev and Kliuchevskii declared the state of the Kievan Rus' to be dissolving at the time of the invasion, while others, typically Soviet historians, like Grekov argued that the main principalities of the Kievan Rus', like Galica-Volhynia at this time, were stable en route to being invaded by the Mongols. The Ukrainian study of their own respective medieval past begins with the study of the Cossack Chronicles. The Chronicles, authored in the 17th and 18th centuries, traces Ukrainian history from biblical eras into the time of the Khazars. in the 1920s Soviet censorship restricted the study and publication of literary work that demonstrated a separate national and historical background for Ukraine as something non-Muscovite, and therefore non-Russian. The era of Romanticism in the 19th century brought with it the idea of human ingenuity as the most relevant driving historical force, and authors like Maksymovych and Kostomarov published works like Books of Genesis of the Ukrainian People to popularize this theory. These works were primarily pro-Ukrainian and othered influences like Poland and Lithuania in the general development of Eastern Europe. Volhynia has at different points in time existed in Ukrainian, Polish, Belarusian, and Lithuanian spaces and so must be qualified in this argument as solely Ukrainian in the perspective of Maksymovych and Kostomarov. Mykhailo Hrushevs'ky in the early 20th century generated what is widely considered the most complete repudiation of the Soviet conception of Ukrainian history.