Michurinsk is the second most populous town in Tambov Oblast, Russia. Population: 98,758 ; 96,093 ; 109,081. Originally known as Kozlov, it …Michurinsk is the second most populous town in Tambov Oblast, Russia. Population: 98,758 ; 96,093 ; 109,081. Originally known as Kozlov, it was founded in 1635 at the northern end of the emerging Belgorod Line, a frontier defense line. A 25-kilometer earthen wall was built eastward across the open steppe effectively blocking the Nogai Trail, a Tatar raiding route. The success of this line led to the building of further lines further south. The settlement was granted town status in 1779.