Following the tribulations of the Mongol invasion, the Russian Church was pivotal in the survival and life of the Russian state. Despite the politically motivated murders of Mikhail of Chernigov and Mikhail of Tver, the Mongols were generally tolerant and even granted tax exemption to the church. Such holy figures as Sergius of Radonezh and Metropolitan Alexis helped the country to withstand years of Mongol rule, and to expand both economically and spiritually. The Trinity monastery north of Moscow, founded by Sergius of Radonezh, became the setting for the flourishing of spiritual art, exemplified by the work of Andrey Rublev, among others. The followers of Sergius founded four hundred monasteries, thus greatly extending the geographical extent of the Grand Duchy of Moscow.