Kislev lies to the north of the Empire. It is a land that borders the fluctuating chaos wastes and as such is often the first place to encounter the marauding bands of chaos that invade the lands of man. Kislev has long been allied with the empire and often sends men to fight for the Emperor. In return the soldiers of the Emperor often venture north to Kislev to aid the wild steppes dwellers.
Kislev is another evocative part of the old world. There's quite a bit of background about the peoples of this frozen land in the Gotrek and Felix novel Daemonslayer
Although there is now a complete Kislev army list, when I first got my models they were just interesting units that I chose to field as part of my Empire force. With the release of the Kislev list and new models I am contemplating expanding my Kislevites into a force in their own right, but for now the lancers and horse archers serve alongside my other Empire troops.
Kislev Models in my army.