Volume 2 is the central volume of the first cycle of Mykhailo Hrushevsky's History of Ukraine-Rus'. In this cycle, the eminent historian explores, chiefly, the history of the Ukrainian lands during the medieval period up until the dissolution of the Rus' state on western Ukrainian territories in the fourteenth century. This middle volume of the cycle describes the crucial Kyiv-centred period of the evolution of the medieval Rus' polity. During that period (the eleventh and twelfth centuries, in particular), the Kyivan princely and military retinue system reached the height of its development. Kyiv controlled vast territories in eastern Europe; the political activities and influence of Rus' princes were at their peak; and Old Rus' culture, art, and literature flourished. However, as Hrushevsky demonstrates, the underlying structure of the Kyivan state was progressively losing strength and falling into decline. He points to two major trends in this process. The first was the detachment of individual lands and the weakening of relations between them. And the second was the decline of the main political centre―Kyiv. The political system of Rus' became greatly weakened by internecine princely conflicts and warfare with nomadic invaders from the steppe. In the end, the onslaught of the most powerful of these nomadic hordes―the Tatar-Mongol army―caused Kyiv's ruin in the 1240s. With this, the role of Kyiv as the political centre of the Old Rus' state came to an end.