Another strategy adopted by the Daniilovichi was to subordinate princes from other branches of the dynasty and simultaneously to expand their own territorial domain. The Moscow princes ruled two sets of territories: lands that belonged to their patrimony
Territorial expansion provided a variety of assets and advantages. One was control over rivers, which had strategic as well as commercial value. By acquiring Serpukhov, Kolomna, and Mozhaisk, Muscovy encompassed the entire length of the Moscow river as well as the segment of the Oka between Kolomna and Serpukhov that formed the southern boundary of the principality. Dmitrii Donskoi later sponsored the construction of walled monasteries at these towns and, thereby, fortified the border. The Moscow princes also controlled a significant section of the Volga river from Kostroma (part of the grand principality of Vladimir) to Nizhnii Novgorod. The principality of Uglich, located between two of the remaining independent principalities, Iaroslavl and Tver, contained another segment of the Volga. Remote from the main body of Moscow’s holdings were Beloozero and the independent but subordinate principality of Ustiug, which commanded the main trade routes that spanned the lands of the north.
Territorial expansion also brought a larger populace under the direct rule of the Muscovite princes. Moscow’s economic and tax base was, correspondingly, broadened. Retainers of subordinated princes, furthermore, were motivated to transfer their allegiance to Moscow, whose own military force and administrative staffs were thereby enlarged and strengthened. The Muscovite princes were able to collect transit and customs fees from the traffic and commercial transactions conducted along their roads and rivers and in their towns. Their control over segments of the Volga also gave them a greater role in the transport of goods down that river to Bulgar and Sarai, hence in the Mongols’ extensive trade network.
Even though it was growing, Moscow’s territory was divided into relatively few apanages. During the reign of Dmitrii Donskoi (1362–89), only one apanage principality (Serpukhov) was carved out of Muscovy’s lands for his cousin. After Dmitrii’s death in 1389, his eldest son (Vasilii I) inherited the throne; each of Dmitrii’s other four sons then received an apanage principality. But due to their failure to produce sons of their own, most of their lands eventually reverted to the grand prince. The only one to survive was the apanage principality of Mozhaisk (later divided into two principalities, Mozhaisk and Vereia). At least until the death of Vasilii I (1425), the few apanage princes of Moscow as well as their senior advisers and military commanders (who held the rank of boyar) were loyal supporters of the grand prince. This internal territorial and political cohesion provided a central, unified core for the expanding state of Muscovy.
The wealth Moscow derived from its increased population, extended lands, and commerce was reflected in the introduction of monumental stone buildings into the wooden town. After the Mongol invasion the princes in north-eastern Rus could not afford to construct major buildings. Tver was the first to accumulate sufficient wealth (by the end of the thirteenth century) to resume the construction of stone cathedrals. Moscow followed: in 1326 its Prince Ivan (the future Grand Prince Ivan Kalita) and Metropolitan Peter co-sponsored the construction of the Church of the Dormition. Soon afterwards four more stone churches were built inside Moscow’s kremlin. Prince Dmitrii rebuilt Moscow’s kremlin fortifications in stone in 1367, fortified some towns and outposts on Muscovy’s frontier, and also ordered the restoration of the Dormition Cathedral in Vladimir. In conjunction with the renewed construction activity, the arts of fresco- and icon-painting also revived. In the 1340s the walls of the kremlin churches were painted with frescos by Byzantine and Russian artists. Those of the Dormition Cathedral in Vladimir were painted with frescos at the commission of Vasilii I by Andrei Rublev, one of the greatest artists of the era.