The map extension is not like that of Rajas. Instead, they added 27 new counties (divided into 8 duchies and 2 kingdoms) to the wasteland on the eastern part of the map. These counties include the Orkhon valley, as well as Karabalgasun and Karakorum. There also new cultures: Uyghur, Khitan, Sogdian and Tocharian.
The mongols themselves (as Khalkha) will be playable even in the CM start date, but will be a tributary of the Uyghurs. The main religions in the area are Manichean (doesn't seem to be getting any mechanics) and Buddhism. The Tarim Basin will also feature Silk Road provinces, probably being one of the sources (the other, I guess, is in India).
There are also new modding features. I'll just copy and paste that bit.
- Added geographical regions that can be checked in triggers if a title or province is contained in a region defined in map/geographical_region.txt. These regions are static throughout the game and are more reliable than using de-jure triggers for events that you want to affect specific places.
- Bookmarks now uses folder structure
- Combat tactics now uses folder structure
- Disease now uses folder structure
- Job actions now uses folder structure
- Job titles now uses folder structure
- Triggered modifiers now uses folder structure
- Added scripted triggers
- Added scripted effects
- Added create_tradepost effect
- Added folder structure to defines
- Added folder structure to modifier_definitions
- Added MAX_WARDS_PER_GUARDIAN to defines
- Added missing commandline argument "debug" to show debug logs
- Possible to append to cultures from several files
- Possible to append to on_actions from several files
- Added trigger technology_can_spread, checking whether technology can spread in the province.
- Added effects set_special_character_title, remove_special_character_title.
- Can now specify a CB to not be displayed in the diplomatic mapmode
- Culture can now decide if you are allowed to raid or not
- Added external province type in map definitions, will not generate a border or text and can be 1 pixel big
- Added global movement speed modifier
- Now can force contract on specific governments which will bypass the opinion limitations using new government system
- Now possible to disable courtiers from receiving MTTH events in defines
- Added effect set_government_type.
- Governments can be modded in the decisions folder.
- Geographical regions can be modded in the map folder.
- County-, duchy- and sub-region tags can now be used to define island- and geographical regions.
- Added region trigger.
- Added flags reinforcing [yes/no] and reinforce_rate_multiplier to the spawn unit effect.
- Added flag maintenance [yes/no] to the spawn unit effect.
- Added flag looting [yes/no] and can_toggle_looting [yes/no] to the spawn unit effect.
- Added trigger is_allowed_to_loot.
- Added on_action on_became_imprisoned_any_reason, that triggers whenever a character becomes imprisoned for any reason.
- Added flag adventurer [yes/no]. Adventure titles work just as temporary titles but do not get destroyed automatically when the holder is in peace. Instead, they are destroyed whenever the holder gains another title or when the holder dies.
- Added effect set_looting and set_can_toggle_looting for units.
- Added character text GetHusbandWifeOpp.
- Added triggers realm_levy_diff, reverse_realm_levy_diff, max_realm_levy_diff and reverse_max_realm_levy_diff.
- Renamed the realm_manpower trigger to realm_levies.
- The break effect now also properly affect tooltips.
- Added effects any_unit, any_army, any_fleet, random_unit, random_army and random_fleet.
- Added trigger any_unit, any_army and any_fleet.
- Added flag seafarer in culture and religion files, helping the AI to determine if coastal provinces is preferred when raiding.
- Added trigger is_seafarer, checking if either the culture or religion have the seafarer flag set.
- Added trigger is_island, checking if the province exists in island_region.txt.
- Added event target most_participating_crusader, used to get the most participating non-theocracy attacker in a war.
- Added on_action on_divorce, which fires whenever a character gets divorced regardless of the reason.
- Quick triggers are now properly checked when you fire an event from another event.
- Added triggers is_[law/government/decision/targetted_decision/title_decision/settlement_decision]_[valid/potential] with parameters key, character, title and settlement.
- Added effects and triggers any_dejure_liege and any_defacto_liege.
- Added event target defacto_liege_title.
- Added effect destroy_settlement.
- Added effect make_primary_settlement.
- Added match_settlement to the spawn unit effect.
- Added event trigger 'log'.
- Earmarked units can now also use the $CULTURE$ parameter.
- Added trigger completely_controls_region.
- Added any_title effect.
- Added effects make_capital_holding and revoke_capital_holding.
- Added trigger is_nomadic.
- Added government trigger.
- The Spawn Unit effect can now take saved event targets as parameters.
- Added nomad flag to the create_title effect.
- Added effect convert_to_nomad and convert_to_fort.
- Added flags ai_fabricate_claims to religion groups.
- Added flags attacking_same_religion_piety_loss and uses_decadence to religions. Decadence will be used if the religion AND government of a character is scripted to use decadece.
- Added flags hire_cost and maintenance_multiplier to retinue subunits.
- Added event scopes [strongest/weakest]_clan_vassal, [strongest/weakest]_clan, [strongest/weakest]_clan_vassal_except_me and [strongest/weakest]_clan_except_me, determined by the number of empty holdings they hold.
- Added event scopes [most/least]_prestigious_clan_vassal, [most/least]_prestigious_clan, [most/least]_prestigious_clan_vassal_except_me and [most/least]_prestigious_clan_except_me.
- Added event scopes [most/least]_populous_clan_vassal, [most/least]_populous_clan, [most/least]_populous_clan_vassal_except_me and [most/least]_populous_clan_except_me.
- Added triggers clan_satisfaction, total_manpower, unused_manpower, raised_manpower, max_manpower, manpower_growth, population, max_population, population_growth, population_and_manpower, max_population_and_manpower and population_and_manpower_growth.
- Added effects manpower and population.
- Added trigger uses_decadence.
- Added nand-trigger.
- Not-triggers will now do a script assert if it contains more than one trigger (where the use of nand- and nor-triggers are recommended to be used instead), but will work as previously.
- Added trade_post_has_building and trade_post_has_any_building triggers.
- Added trigger is_settlement_type_allowed.
- Added effects create_fort, destroy_fort, seize_fort, random_fort and any_fort.
- Added triggers any_fort, num_of_forts, num_of_forts_diff, has_fort, fort_has_building and fort_has_any_building.
- Added event scope trade_post_owner.
- Added trigger has_castle, has_temple, has_city and has_tribal.
- Added trigger has_settlement_construction.
- Added triggers is_[law/government/decision/targetted_decision/title_decision/settlement_decision/trade_post_decision/fort_decision]_[allowed/potential].
- Added triggers num_of_[subrealm/demesne]_[castles/cities/temples/tribes/empty_provinces].
- Added trigger holding_diff.
- Added effects set_title_landless, set_title_adventurer and set_title_nomad.
- Added forbidden_raid_target opinion modifier, which disallows looting against that character.
- Job action script can now properly use the various job title event scopes.
- Added triggers has_feud_with and any_feud_rival_clan.
- Added triggers clan_opinion, reverse_clan_opinion, their_clan_opinion, clan_opinion_diff and reverse_clan_opinion_diff.
- Added is_high_prio flag to minor titles, determining whether an alert should be shown or not if that title is available to grant.
- Added triggers num_of_king_titles_in_realm, num_of_duke_titles_in_realm, num_of_count_titles_in_realm, num_of_baron_titles_in_realm, num_of_titles_in_realm.
- Added effect unsafe_give_minor_title.
- Added modifiers clan_sentiment, max_manpower, max_manpower_mult, max_population, max_population_mult, manpower_growth and population_growth, currently applicable on characters and the capital.
- Added modifiers retinue_maintenence_cost and horde_maintenence_cost, currently applicable on characters, family palaces and the capital.
- Added is_active_trigger to buildings. Any modifier from buildings that are not considered active will not apply until the is_active_trigger is properly validated.
- Added modifier global_winter_supply, currently applicable on the capital.
- commander_limit can now be scripted in buildings for capital settlements, increasing the number of commanders a ruler can have.
- moved_capital_months_mult can now be scripted for capital buildings and modifies the delay for how often one can change capital, if their government allows for more frequent switching than once per lifetime.
- The set_defacto_liege effect now works on titles as well.
- Added on_actions on_battle_won_owner and on_battle_lost_owner.
- Added modifiers global_trade_route_wealth, global_trade_route_value, global_tradevalue and global_tradevalue_mult, applicable on the capital of holders of a trade post.
- Trade post buildings will now also have an effect in the capital settlement, not only the family palace.
- Fixed bug where the targetted decision filters realm and sub_realm did not properly check the court of the top liege or the current character.
- Added trigger religion_allows_female_temple_holders.
- The spawn_unit effect will now spawn units on any other unit if there is no other valid location (instead of not spawning the units at all).
As for a few misc features, we can now move prisoners freely between the regular dungeon, the oubliette and house arrest. Banishment of characters has also been changed, so that they instead are forced to abdicate to their new heir (you no longer steal their titles). There is now more loot in tribal counties so they are raided more. The name of the opinion modifiers now show up in tooltips instead of "opinion changes by -10"