Entire Lithuania and neighbouring south-eastern Latvia (neighbouring regions to Belarus) did not have Finnic settlements or Finnish influence. Many results show Lithuanian population is similar to me among top 3-5 population. But not Finnish.
The approximate border between Baltic & Slavic populations and Finno-Ugric is the line between Riga and Moscow. North-east are Finno-Ugric, while south-west are Baltic and Slavic.