Landless raiding adventurers may appear and harass a region for a time or try to conquer land and settle.
Send your unruly sons or brothers away as soldiers of fortune.
The Silk Road, with corresponding dynamic trade mechanics and conflicts.
Non-nomadic rulers will have special options for combating nomads, such as constructing forts in wild enemy lands.
Over a hundred new events add extra color and flair to the Steppes and Central Asia.
Also, the ruler’s power must be balanced against the interests of the various Clans within the realm (Clans are not normal vassals, but rather distinct families and factions within the nomad group). These function in a radically different way from sedentary societies - you manage populations instead of holdings, and armies are raised based on population size.
Nomadic government available for steppe cultures.
Tarim Basin and large parts of Mongolia added to map.
The full list is below, and the expansion is available here. There's also over a hundred new events, new "dynamic trade mechanics and conflicts" thanks to the The Silk Road, and Mongol invasions have been reworked.