As near as I can make it out, they appear to be artillery focused, combined arms, fortress type units (hopefully that makes sense) specifically to secure the Russian-Chinese border or Russian-Japanese border.
The following webpage gives some info on one such unit but it is best read in conjunction with the pages from wikipedia (links given below)
https://military.wikia.org/wiki/126t...llery_Division
https://en.wikipedia.org/wiki/69th_C...rigade_(Russia)
https://en.wikipedia.org/wiki/18th_M...llery_Division