Cossack raiders => Don Cossacks  => Black Sea Cossacks  => Cossacks Regiment  A light cavalry line, with faster movement and creation speed.
Imperial Guard  Russia's cuirassier unit, on par with British Scots Greys.
Bardiche levy [1-2] => Opolchenies [3-4]
streltsy musketeers  => Petrine pekhotnitsy  => Imperial pekhotnitsy  => Rifle pekhotnitsy  No ramp, and while rapid-shooting, Pekhotnitsy have poor accuracy and do not receive armour until the Industrial Era - and also cannot be upgraded to modern infantry.
Cossack bowmen  => Serdiuks  (these units are like foot mercenaries)
Pavlovski Grenadiers  => Imperial Guard Grenadiers  These units are on par with the British heavy line.
Nomadic hunters  fierce horse-riding archers from the steppes of Central Asia, lost to dragoons.
War barge  shared with jungle civs. Weak, but still cheap enough to be built in huge numbers.
Gorodsky Sobor - performs taxation and religion research, and is the main stopping point for your auxiliary units.
Military-industrial complex (requires 6 levels of Military research; available from )
Units heal within your borders
Reduces the build time of ships, foundry units and aircraft
Has a +10 oil and +10 metal bonus (once 3rd Green researched).
Reduces the knowledge costs of science research and the research time for military research.
Grants access to upgrades that allow for the creation of dreadnoughts, howitzers and heavy machine guns in .
Has a facility for building recoilless gun infantry and tanks (different non-European sides build different tanks in  - Tanks are powerful mechanised units that destroy all other units, but have their own weaknesses - recoilless guns destroy them; they are vulnerable from aircraft attack; a direct hit from a cannon could potentially destroy them; and they are slower than tankettes, although they are much powerful in a shot-for-shot battle.)