One prince who was particularly good at this was known as Ivan Kalita, using my Russian I can tell you that that translates to Johnny Moneybags. As my Russian professor would tell you, I'm a creative translator. All this loot helped Moscow expand their influence and buy up principalities. The Mongols also helped them more directly by attacking their enemies. Plus, Moscow was at the headwaters of four rivers, which made it well positioned for trade. And because they were kind of the allies of the Mongols, the Mongols rarely attacked them, which meant that lots of people went to Moscow because it was relatively safe, including churchy people. And in fact, Moscow became the seat of the Eastern Orthodox Church in 1325, when the metropolitan Peter moved there.