Lithuanians, bulgarians, cumans and tatars are new civilizations according to AOE 2 DE Steam achievements.
https://steamdb.info/app/813780/stats/ - LITHUANIANS_VICTORY, bulgarians_victory, cumans_victory, tatars_victory.
Bulgarians, cumans and tatars will each get a campaign - ACHIEVEMENT_CAMPAIGN_BULGARIAN_COMPLETED, ACHIEVEMENT_CAMPAIGN_CUMAN_COMPLETED, ACHIEVEMENT_CAMPAIGN_TATAR_COMPLETED.