145 years continuously (and on and off before then, dating back to Peter The Great), then 74 years under the Soviets. A pretty good chunk of time IMO.
"Soviets" was a union of 15 republics, not one big russia.
To your original comment: russia absolutely didn't behave nice on that land at any time in history regardless of who they were at war with.
https://www.google.com/search?q=belarus+part+of+russian+empi...
and I'm not your man